メールクライアント UI

クラス設計とコンストラクタ

App40クラスにアプリの全機能をまとめています。__init__メソッドでウィンドウの基本設定を行い、_build_ui()でUI構築、process()でメイン処理を担当します。この分離により、各メソッドの責任が明確になりコードが読みやすくなります。

import tkinter as tk
from tkinter import ttk, messagebox, scrolledtext
import smtplib
import imaplib
import email
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.header import decode_header
import threading
import os


class App40:
    """メールクライアント UI"""

    def __init__(self, root):
        self.root = root
        self.root.title("メールクライアント UI")
        self.root.geometry("1000x680")
        self.root.configure(bg="#f8f9fc")
        self._messages = []
        self._imap = None
        self._build_ui()

    def _build_ui(self):
        header = tk.Frame(self.root, bg="#1a237e", pady=8)
        header.pack(fill=tk.X)
        tk.Label(header, text="📧 メールクライアント UI",
                 font=("Noto Sans JP", 13, "bold"),
                 bg="#1a237e", fg="white").pack(side=tk.LEFT, padx=12)

        notebook = ttk.Notebook(self.root)
        notebook.pack(fill=tk.BOTH, expand=True, padx=6, pady=6)

        # ── 受信タブ ──────────────────────────────────────────────
        recv_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(recv_tab, text="📥 受信")
        self._build_recv_tab(recv_tab)

        # ── 送信タブ ──────────────────────────────────────────────
        send_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(send_tab, text="✉ 送信")
        self._build_send_tab(send_tab)

        # ── アカウント設定タブ ────────────────────────────────────
        settings_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(settings_tab, text="⚙ 設定")
        self._build_settings_tab(settings_tab)

        self.status_var = tk.StringVar(value="設定タブでアカウントを設定してください")
        tk.Label(self.root, textvariable=self.status_var,
                 bg="#dde", font=("Arial", 9), anchor="w", padx=8
                 ).pack(fill=tk.X, side=tk.BOTTOM)

    # ── 受信タブ ──────────────────────────────────────────────────

    def _build_recv_tab(self, parent):
        # ツールバー
        bar = tk.Frame(parent, bg="#f8f9fc")
        bar.pack(fill=tk.X, padx=8, pady=6)
        ttk.Button(bar, text="🔄 メールを取得",
                   command=self._fetch_mail).pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="フォルダ:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(12, 2))
        self.folder_var = tk.StringVar(value="INBOX")
        self.folder_cb = ttk.Combobox(bar, textvariable=self.folder_var,
                                       values=["INBOX", "Sent", "Drafts", "Trash"],
                                       width=14)
        self.folder_cb.pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="件数:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(8, 2))
        self.fetch_count_var = tk.IntVar(value=20)
        ttk.Spinbox(bar, from_=5, to=200,
                    textvariable=self.fetch_count_var, width=5).pack(side=tk.LEFT)

        # メール一覧 + 本文
        paned = ttk.PanedWindow(parent, orient=tk.VERTICAL)
        paned.pack(fill=tk.BOTH, expand=True, padx=8)

        # メール一覧
        list_f = tk.Frame(paned, bg="#f8f9fc")
        paned.add(list_f, weight=1)
        cols = ("from_", "subject", "date", "size")
        self.mail_tree = ttk.Treeview(list_f, columns=cols,
                                       show="headings", height=8)
        for c, h, w in [("from_", "差出人", 180), ("subject", "件名", 300),
                         ("date", "日時", 140), ("size", "サイズ", 70)]:
            self.mail_tree.heading(c, text=h)
            self.mail_tree.column(c, width=w, minwidth=40)
        sb = ttk.Scrollbar(list_f, command=self.mail_tree.yview)
        self.mail_tree.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.mail_tree.pack(fill=tk.BOTH, expand=True)
        self.mail_tree.bind("<<TreeviewSelect>>", self._on_mail_select)
        self.mail_tree.tag_configure("unread", font=("Arial", 10, "bold"))
        self.mail_tree.tag_configure("read", font=("Arial", 10))

        # 本文
        body_f = ttk.LabelFrame(paned, text="本文", padding=4)
        paned.add(body_f, weight=2)

        # ヘッダー情報
        self.mail_header_var = tk.StringVar(value="")
        tk.Label(body_f, textvariable=self.mail_header_var,
                 bg="#e8eaf6", fg="#283593", font=("Arial", 9),
                 anchor="w", padx=6).pack(fill=tk.X, pady=2)

        self.body_text = tk.Text(body_f, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  state=tk.DISABLED, wrap=tk.WORD)
        body_sb = ttk.Scrollbar(body_f, command=self.body_text.yview)
        self.body_text.configure(yscrollcommand=body_sb.set)
        body_sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.body_text.pack(fill=tk.BOTH, expand=True)

        # 返信ボタン
        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="↩ 返信",
                   command=self._reply).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 削除",
                   command=self._delete_mail).pack(side=tk.LEFT, padx=4)

        self.recv_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.recv_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 送信タブ ──────────────────────────────────────────────────

    def _build_send_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        for lbl, attr, show in [("宛先 (To):", "to_var", ""),
                                 ("CC:", "cc_var", ""),
                                 ("件名:", "subject_var", "")]:
            row = tk.Frame(parent, bg="#f8f9fc")
            row.pack(fill=tk.X, padx=8, pady=3)
            tk.Label(row, text=lbl, width=12, anchor="e", **lbl_s).pack(side=tk.LEFT)
            var = tk.StringVar()
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=60).pack(side=tk.LEFT, padx=4,
                                                              fill=tk.X, expand=True)

        # 本文
        tk.Label(parent, text="本文:", **lbl_s).pack(anchor="w", padx=8, pady=2)
        self.send_body = tk.Text(parent, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  height=16)
        sb = ttk.Scrollbar(parent, command=self.send_body.yview)
        self.send_body.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.send_body.pack(fill=tk.BOTH, expand=True, padx=8, pady=4)

        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="📤 送信",
                   command=self._send_mail).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 クリア",
                   command=self._clear_compose).pack(side=tk.LEFT, padx=4)

        self.send_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.send_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 設定タブ ──────────────────────────────────────────────────

    def _build_settings_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        # 送信 (SMTP)
        smtp_f = ttk.LabelFrame(parent, text="SMTP設定（送信）", padding=10)
        smtp_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("SMTPサーバー:", "smtp_host_var", "smtp.gmail.com", ""),
            ("ポート:", "smtp_port_var", "587", ""),
            ("ユーザー:", "smtp_user_var", "", ""),
            ("パスワード:", "smtp_pass_var", "", "*"),
        ]:
            row = tk.Frame(smtp_f, bg=smtp_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.smtp_tls_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(smtp_f, text="TLS/STARTTLS を使用",
                         variable=self.smtp_tls_var).pack(anchor="w")

        # 受信 (IMAP)
        imap_f = ttk.LabelFrame(parent, text="IMAP設定（受信）", padding=10)
        imap_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("IMAPサーバー:", "imap_host_var", "imap.gmail.com", ""),
            ("ポート:", "imap_port_var", "993", ""),
        ]:
            row = tk.Frame(imap_f, bg=imap_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.imap_ssl_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(imap_f, text="SSL を使用",
                         variable=self.imap_ssl_var).pack(anchor="w")

        # メモ
        tk.Label(parent,
                 text="※ Gmailの場合はアプリパスワードを使用してください。\n"
                      "  Google アカウント → セキュリティ → アプリパスワードで生成。",
                 bg="#fff3cd", fg="#856404", font=("Arial", 9),
                 anchor="w", padx=8, justify=tk.LEFT).pack(fill=tk.X, padx=8, pady=4)

        ttk.Button(parent, text="💾 設定を保存 / 接続テスト",
                   command=self._test_connection).pack(padx=8, pady=4)

    # ── メール操作 ────────────────────────────────────────────────

    def _fetch_mail(self):
        host = self.imap_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでIMAPサーバーを設定してください")
            return
        self.recv_progress.start(10)
        self.status_var.set("メール取得中...")
        threading.Thread(target=self._do_fetch_mail, daemon=True).start()

    def _do_fetch_mail(self):
        try:
            host = self.imap_host_var.get().strip()
            port = int(self.imap_port_var.get() or 993)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            folder = self.folder_var.get()
            count = self.fetch_count_var.get()

            if self.imap_ssl_var.get():
                imap = imaplib.IMAP4_SSL(host, port)
            else:
                imap = imaplib.IMAP4(host, port)

            imap.login(user, passwd)
            imap.select(folder)

            # 最新N件のIDを取得
            _, data = imap.search(None, "ALL")
            ids = data[0].split()
            fetch_ids = ids[-count:] if len(ids) >= count else ids
            fetch_ids = list(reversed(fetch_ids))

            messages = []
            for uid in fetch_ids:
                _, msg_data = imap.fetch(uid, "(RFC822.SIZE FLAGS RFC822.HEADER)")
                if not msg_data or not msg_data[0]:
                    continue
                raw_header = None
                size = 0
                flags = ""
                for part in msg_data:
                    if isinstance(part, tuple):
                        info = part[0].decode()
                        if "RFC822.SIZE" in info:
                            import re
                            m = re.search(r"RFC822\.SIZE (\d+)", info)
                            if m:
                                size = int(m.group(1))
                        if "FLAGS" in info:
                            flags = info
                        raw_header = part[1]
                if raw_header is None:
                    continue
                try:
                    msg = email.message_from_bytes(raw_header)
                    from_ = self._decode_header(msg.get("From", ""))
                    subject = self._decode_header(msg.get("Subject", ""))
                    date = msg.get("Date", "")[:25]
                    unread = "\\Seen" not in flags
                    messages.append({
                        "uid": uid,
                        "from": from_,
                        "subject": subject,
                        "date": date,
                        "size": size,
                        "unread": unread,
                    })
                except Exception:
                    pass

            self._imap = imap
            self._messages = messages
            self.root.after(0, self._show_mail_list, messages)
        except Exception as e:
            self.root.after(0, self.recv_progress.stop)
            self.root.after(0, self.status_var.set, f"取得エラー: {e}")

    def _show_mail_list(self, messages):
        self.recv_progress.stop()
        self.mail_tree.delete(*self.mail_tree.get_children())
        for msg in messages:
            tag = "unread" if msg.get("unread") else "read"
            self.mail_tree.insert("", "end",
                                   iid=str(msg["uid"]),
                                   values=(msg["from"][:30],
                                           msg["subject"][:60],
                                           msg["date"],
                                           self._fmt_size(msg["size"])),
                                   tags=(tag,))
        self.status_var.set(f"{len(messages)} 件取得")

    def _on_mail_select(self, event):
        sel = self.mail_tree.selection()
        if not sel or not self._imap:
            return
        uid = sel[0].encode()
        threading.Thread(target=self._load_mail_body,
                         args=(uid,), daemon=True).start()

    def _load_mail_body(self, uid):
        try:
            _, data = self._imap.fetch(uid, "(RFC822)")
            if not data or not data[0]:
                return
            raw = data[0][1]
            msg = email.message_from_bytes(raw)
            from_ = self._decode_header(msg.get("From", ""))
            subject = self._decode_header(msg.get("Subject", ""))
            date = msg.get("Date", "")
            body = self._extract_body(msg)
            self.root.after(0, self._show_body, from_, subject, date, body)
        except Exception as e:
            self.root.after(0, self.status_var.set, f"本文取得エラー: {e}")

    def _extract_body(self, msg):
        body = ""
        if msg.is_multipart():
            for part in msg.walk():
                ct = part.get_content_type()
                cd = str(part.get("Content-Disposition") or "")
                if ct == "text/plain" and "attachment" not in cd:
                    payload = part.get_payload(decode=True)
                    if payload:
                        charset = part.get_content_charset() or "utf-8"
                        body = payload.decode(charset, errors="replace")
                        break
        else:
            payload = msg.get_payload(decode=True)
            if payload:
                charset = msg.get_content_charset() or "utf-8"
                body = payload.decode(charset, errors="replace")
        return body

    def _show_body(self, from_, subject, date, body):
        self.mail_header_var.set(f"From: {from_}  |  件名: {subject}  |  日付: {date}")
        self.body_text.config(state=tk.NORMAL)
        self.body_text.delete("1.0", tk.END)
        self.body_text.insert("1.0", body)
        self.body_text.config(state=tk.DISABLED)

    def _decode_header(self, value):
        if not value:
            return ""
        parts = decode_header(value)
        decoded = []
        for part, enc in parts:
            if isinstance(part, bytes):
                decoded.append(part.decode(enc or "utf-8", errors="replace"))
            else:
                decoded.append(part)
        return "".join(decoded)

    def _reply(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        uid = sel[0]
        msg_data = next((m for m in self._messages if str(m["uid"]) == uid), None)
        if msg_data:
            self.to_var.set(msg_data.get("from", ""))
            self.subject_var.set("Re: " + msg_data.get("subject", ""))

    def _delete_mail(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        if messagebox.askyesno("確認", "選択したメールを削除しますか?") and self._imap:
            for uid in sel:
                try:
                    self._imap.store(uid.encode(), "+FLAGS", "\\Deleted")
                except Exception:
                    pass
            try:
                self._imap.expunge()
            except Exception:
                pass
            self._fetch_mail()

    # ── 送信 ─────────────────────────────────────────────────────

    def _send_mail(self):
        to = self.to_var.get().strip()
        if not to:
            messagebox.showwarning("警告", "宛先を入力してください")
            return
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでSMTPサーバーを設定してください")
            return
        self.send_progress.start(10)
        threading.Thread(target=self._do_send_mail, daemon=True).start()

    def _do_send_mail(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            to = self.to_var.get().strip()
            cc = self.cc_var.get().strip()
            subject = self.subject_var.get().strip()
            body = self.send_body.get("1.0", tk.END).strip()

            msg = MIMEMultipart("alternative")
            msg["From"] = user
            msg["To"] = to
            if cc:
                msg["Cc"] = cc
            msg["Subject"] = subject
            msg.attach(MIMEText(body, "plain", "utf-8"))

            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=15)
                smtp.ehlo()
                smtp.starttls()
                smtp.ehlo()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=15)

            smtp.login(user, passwd)
            recipients = [to] + ([cc] if cc else [])
            smtp.sendmail(user, recipients, msg.as_string())
            smtp.quit()

            self.root.after(0, self.send_progress.stop)
            self.root.after(0, self.status_var.set, f"送信完了: {to}")
            self.root.after(0, messagebox.showinfo, "完了", "メールを送信しました")
        except Exception as e:
            self.root.after(0, self.send_progress.stop)
            self.root.after(0, messagebox.showerror, "送信エラー", str(e))

    def _clear_compose(self):
        self.to_var.set("")
        self.cc_var.set("")
        self.subject_var.set("")
        self.send_body.delete("1.0", tk.END)

    def _test_connection(self):
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "SMTPサーバーを入力してください")
            return
        self.status_var.set("接続テスト中...")
        threading.Thread(target=self._do_test_connection, daemon=True).start()

    def _do_test_connection(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=10)
                smtp.ehlo()
                smtp.starttls()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=10)
            smtp.quit()
            self.root.after(0, self.status_var.set,
                            f"✅ SMTP接続成功: {host}:{port}")
        except Exception as e:
            self.root.after(0, self.status_var.set,
                            f"❌ SMTP接続失敗: {e}")

    def _fmt_size(self, size):
        if size < 1024:
            return f"{size}B"
        elif size < 1024 * 1024:
            return f"{size//1024}KB"
        return f"{size//1024//1024}MB"


if __name__ == "__main__":
    root = tk.Tk()
    app = App40(root)
    root.mainloop()

LabelFrameによるセクション分け

ttk.LabelFrame を使うことで、入力エリアと結果エリアを視覚的に分けられます。padding引数でフレーム内の余白を設定し、見やすいレイアウトを実現しています。

import tkinter as tk
from tkinter import ttk, messagebox, scrolledtext
import smtplib
import imaplib
import email
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.header import decode_header
import threading
import os


class App40:
    """メールクライアント UI"""

    def __init__(self, root):
        self.root = root
        self.root.title("メールクライアント UI")
        self.root.geometry("1000x680")
        self.root.configure(bg="#f8f9fc")
        self._messages = []
        self._imap = None
        self._build_ui()

    def _build_ui(self):
        header = tk.Frame(self.root, bg="#1a237e", pady=8)
        header.pack(fill=tk.X)
        tk.Label(header, text="📧 メールクライアント UI",
                 font=("Noto Sans JP", 13, "bold"),
                 bg="#1a237e", fg="white").pack(side=tk.LEFT, padx=12)

        notebook = ttk.Notebook(self.root)
        notebook.pack(fill=tk.BOTH, expand=True, padx=6, pady=6)

        # ── 受信タブ ──────────────────────────────────────────────
        recv_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(recv_tab, text="📥 受信")
        self._build_recv_tab(recv_tab)

        # ── 送信タブ ──────────────────────────────────────────────
        send_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(send_tab, text="✉ 送信")
        self._build_send_tab(send_tab)

        # ── アカウント設定タブ ────────────────────────────────────
        settings_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(settings_tab, text="⚙ 設定")
        self._build_settings_tab(settings_tab)

        self.status_var = tk.StringVar(value="設定タブでアカウントを設定してください")
        tk.Label(self.root, textvariable=self.status_var,
                 bg="#dde", font=("Arial", 9), anchor="w", padx=8
                 ).pack(fill=tk.X, side=tk.BOTTOM)

    # ── 受信タブ ──────────────────────────────────────────────────

    def _build_recv_tab(self, parent):
        # ツールバー
        bar = tk.Frame(parent, bg="#f8f9fc")
        bar.pack(fill=tk.X, padx=8, pady=6)
        ttk.Button(bar, text="🔄 メールを取得",
                   command=self._fetch_mail).pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="フォルダ:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(12, 2))
        self.folder_var = tk.StringVar(value="INBOX")
        self.folder_cb = ttk.Combobox(bar, textvariable=self.folder_var,
                                       values=["INBOX", "Sent", "Drafts", "Trash"],
                                       width=14)
        self.folder_cb.pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="件数:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(8, 2))
        self.fetch_count_var = tk.IntVar(value=20)
        ttk.Spinbox(bar, from_=5, to=200,
                    textvariable=self.fetch_count_var, width=5).pack(side=tk.LEFT)

        # メール一覧 + 本文
        paned = ttk.PanedWindow(parent, orient=tk.VERTICAL)
        paned.pack(fill=tk.BOTH, expand=True, padx=8)

        # メール一覧
        list_f = tk.Frame(paned, bg="#f8f9fc")
        paned.add(list_f, weight=1)
        cols = ("from_", "subject", "date", "size")
        self.mail_tree = ttk.Treeview(list_f, columns=cols,
                                       show="headings", height=8)
        for c, h, w in [("from_", "差出人", 180), ("subject", "件名", 300),
                         ("date", "日時", 140), ("size", "サイズ", 70)]:
            self.mail_tree.heading(c, text=h)
            self.mail_tree.column(c, width=w, minwidth=40)
        sb = ttk.Scrollbar(list_f, command=self.mail_tree.yview)
        self.mail_tree.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.mail_tree.pack(fill=tk.BOTH, expand=True)
        self.mail_tree.bind("<<TreeviewSelect>>", self._on_mail_select)
        self.mail_tree.tag_configure("unread", font=("Arial", 10, "bold"))
        self.mail_tree.tag_configure("read", font=("Arial", 10))

        # 本文
        body_f = ttk.LabelFrame(paned, text="本文", padding=4)
        paned.add(body_f, weight=2)

        # ヘッダー情報
        self.mail_header_var = tk.StringVar(value="")
        tk.Label(body_f, textvariable=self.mail_header_var,
                 bg="#e8eaf6", fg="#283593", font=("Arial", 9),
                 anchor="w", padx=6).pack(fill=tk.X, pady=2)

        self.body_text = tk.Text(body_f, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  state=tk.DISABLED, wrap=tk.WORD)
        body_sb = ttk.Scrollbar(body_f, command=self.body_text.yview)
        self.body_text.configure(yscrollcommand=body_sb.set)
        body_sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.body_text.pack(fill=tk.BOTH, expand=True)

        # 返信ボタン
        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="↩ 返信",
                   command=self._reply).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 削除",
                   command=self._delete_mail).pack(side=tk.LEFT, padx=4)

        self.recv_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.recv_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 送信タブ ──────────────────────────────────────────────────

    def _build_send_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        for lbl, attr, show in [("宛先 (To):", "to_var", ""),
                                 ("CC:", "cc_var", ""),
                                 ("件名:", "subject_var", "")]:
            row = tk.Frame(parent, bg="#f8f9fc")
            row.pack(fill=tk.X, padx=8, pady=3)
            tk.Label(row, text=lbl, width=12, anchor="e", **lbl_s).pack(side=tk.LEFT)
            var = tk.StringVar()
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=60).pack(side=tk.LEFT, padx=4,
                                                              fill=tk.X, expand=True)

        # 本文
        tk.Label(parent, text="本文:", **lbl_s).pack(anchor="w", padx=8, pady=2)
        self.send_body = tk.Text(parent, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  height=16)
        sb = ttk.Scrollbar(parent, command=self.send_body.yview)
        self.send_body.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.send_body.pack(fill=tk.BOTH, expand=True, padx=8, pady=4)

        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="📤 送信",
                   command=self._send_mail).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 クリア",
                   command=self._clear_compose).pack(side=tk.LEFT, padx=4)

        self.send_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.send_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 設定タブ ──────────────────────────────────────────────────

    def _build_settings_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        # 送信 (SMTP)
        smtp_f = ttk.LabelFrame(parent, text="SMTP設定（送信）", padding=10)
        smtp_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("SMTPサーバー:", "smtp_host_var", "smtp.gmail.com", ""),
            ("ポート:", "smtp_port_var", "587", ""),
            ("ユーザー:", "smtp_user_var", "", ""),
            ("パスワード:", "smtp_pass_var", "", "*"),
        ]:
            row = tk.Frame(smtp_f, bg=smtp_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.smtp_tls_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(smtp_f, text="TLS/STARTTLS を使用",
                         variable=self.smtp_tls_var).pack(anchor="w")

        # 受信 (IMAP)
        imap_f = ttk.LabelFrame(parent, text="IMAP設定（受信）", padding=10)
        imap_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("IMAPサーバー:", "imap_host_var", "imap.gmail.com", ""),
            ("ポート:", "imap_port_var", "993", ""),
        ]:
            row = tk.Frame(imap_f, bg=imap_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.imap_ssl_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(imap_f, text="SSL を使用",
                         variable=self.imap_ssl_var).pack(anchor="w")

        # メモ
        tk.Label(parent,
                 text="※ Gmailの場合はアプリパスワードを使用してください。\n"
                      "  Google アカウント → セキュリティ → アプリパスワードで生成。",
                 bg="#fff3cd", fg="#856404", font=("Arial", 9),
                 anchor="w", padx=8, justify=tk.LEFT).pack(fill=tk.X, padx=8, pady=4)

        ttk.Button(parent, text="💾 設定を保存 / 接続テスト",
                   command=self._test_connection).pack(padx=8, pady=4)

    # ── メール操作 ────────────────────────────────────────────────

    def _fetch_mail(self):
        host = self.imap_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでIMAPサーバーを設定してください")
            return
        self.recv_progress.start(10)
        self.status_var.set("メール取得中...")
        threading.Thread(target=self._do_fetch_mail, daemon=True).start()

    def _do_fetch_mail(self):
        try:
            host = self.imap_host_var.get().strip()
            port = int(self.imap_port_var.get() or 993)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            folder = self.folder_var.get()
            count = self.fetch_count_var.get()

            if self.imap_ssl_var.get():
                imap = imaplib.IMAP4_SSL(host, port)
            else:
                imap = imaplib.IMAP4(host, port)

            imap.login(user, passwd)
            imap.select(folder)

            # 最新N件のIDを取得
            _, data = imap.search(None, "ALL")
            ids = data[0].split()
            fetch_ids = ids[-count:] if len(ids) >= count else ids
            fetch_ids = list(reversed(fetch_ids))

            messages = []
            for uid in fetch_ids:
                _, msg_data = imap.fetch(uid, "(RFC822.SIZE FLAGS RFC822.HEADER)")
                if not msg_data or not msg_data[0]:
                    continue
                raw_header = None
                size = 0
                flags = ""
                for part in msg_data:
                    if isinstance(part, tuple):
                        info = part[0].decode()
                        if "RFC822.SIZE" in info:
                            import re
                            m = re.search(r"RFC822\.SIZE (\d+)", info)
                            if m:
                                size = int(m.group(1))
                        if "FLAGS" in info:
                            flags = info
                        raw_header = part[1]
                if raw_header is None:
                    continue
                try:
                    msg = email.message_from_bytes(raw_header)
                    from_ = self._decode_header(msg.get("From", ""))
                    subject = self._decode_header(msg.get("Subject", ""))
                    date = msg.get("Date", "")[:25]
                    unread = "\\Seen" not in flags
                    messages.append({
                        "uid": uid,
                        "from": from_,
                        "subject": subject,
                        "date": date,
                        "size": size,
                        "unread": unread,
                    })
                except Exception:
                    pass

            self._imap = imap
            self._messages = messages
            self.root.after(0, self._show_mail_list, messages)
        except Exception as e:
            self.root.after(0, self.recv_progress.stop)
            self.root.after(0, self.status_var.set, f"取得エラー: {e}")

    def _show_mail_list(self, messages):
        self.recv_progress.stop()
        self.mail_tree.delete(*self.mail_tree.get_children())
        for msg in messages:
            tag = "unread" if msg.get("unread") else "read"
            self.mail_tree.insert("", "end",
                                   iid=str(msg["uid"]),
                                   values=(msg["from"][:30],
                                           msg["subject"][:60],
                                           msg["date"],
                                           self._fmt_size(msg["size"])),
                                   tags=(tag,))
        self.status_var.set(f"{len(messages)} 件取得")

    def _on_mail_select(self, event):
        sel = self.mail_tree.selection()
        if not sel or not self._imap:
            return
        uid = sel[0].encode()
        threading.Thread(target=self._load_mail_body,
                         args=(uid,), daemon=True).start()

    def _load_mail_body(self, uid):
        try:
            _, data = self._imap.fetch(uid, "(RFC822)")
            if not data or not data[0]:
                return
            raw = data[0][1]
            msg = email.message_from_bytes(raw)
            from_ = self._decode_header(msg.get("From", ""))
            subject = self._decode_header(msg.get("Subject", ""))
            date = msg.get("Date", "")
            body = self._extract_body(msg)
            self.root.after(0, self._show_body, from_, subject, date, body)
        except Exception as e:
            self.root.after(0, self.status_var.set, f"本文取得エラー: {e}")

    def _extract_body(self, msg):
        body = ""
        if msg.is_multipart():
            for part in msg.walk():
                ct = part.get_content_type()
                cd = str(part.get("Content-Disposition") or "")
                if ct == "text/plain" and "attachment" not in cd:
                    payload = part.get_payload(decode=True)
                    if payload:
                        charset = part.get_content_charset() or "utf-8"
                        body = payload.decode(charset, errors="replace")
                        break
        else:
            payload = msg.get_payload(decode=True)
            if payload:
                charset = msg.get_content_charset() or "utf-8"
                body = payload.decode(charset, errors="replace")
        return body

    def _show_body(self, from_, subject, date, body):
        self.mail_header_var.set(f"From: {from_}  |  件名: {subject}  |  日付: {date}")
        self.body_text.config(state=tk.NORMAL)
        self.body_text.delete("1.0", tk.END)
        self.body_text.insert("1.0", body)
        self.body_text.config(state=tk.DISABLED)

    def _decode_header(self, value):
        if not value:
            return ""
        parts = decode_header(value)
        decoded = []
        for part, enc in parts:
            if isinstance(part, bytes):
                decoded.append(part.decode(enc or "utf-8", errors="replace"))
            else:
                decoded.append(part)
        return "".join(decoded)

    def _reply(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        uid = sel[0]
        msg_data = next((m for m in self._messages if str(m["uid"]) == uid), None)
        if msg_data:
            self.to_var.set(msg_data.get("from", ""))
            self.subject_var.set("Re: " + msg_data.get("subject", ""))

    def _delete_mail(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        if messagebox.askyesno("確認", "選択したメールを削除しますか?") and self._imap:
            for uid in sel:
                try:
                    self._imap.store(uid.encode(), "+FLAGS", "\\Deleted")
                except Exception:
                    pass
            try:
                self._imap.expunge()
            except Exception:
                pass
            self._fetch_mail()

    # ── 送信 ─────────────────────────────────────────────────────

    def _send_mail(self):
        to = self.to_var.get().strip()
        if not to:
            messagebox.showwarning("警告", "宛先を入力してください")
            return
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでSMTPサーバーを設定してください")
            return
        self.send_progress.start(10)
        threading.Thread(target=self._do_send_mail, daemon=True).start()

    def _do_send_mail(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            to = self.to_var.get().strip()
            cc = self.cc_var.get().strip()
            subject = self.subject_var.get().strip()
            body = self.send_body.get("1.0", tk.END).strip()

            msg = MIMEMultipart("alternative")
            msg["From"] = user
            msg["To"] = to
            if cc:
                msg["Cc"] = cc
            msg["Subject"] = subject
            msg.attach(MIMEText(body, "plain", "utf-8"))

            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=15)
                smtp.ehlo()
                smtp.starttls()
                smtp.ehlo()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=15)

            smtp.login(user, passwd)
            recipients = [to] + ([cc] if cc else [])
            smtp.sendmail(user, recipients, msg.as_string())
            smtp.quit()

            self.root.after(0, self.send_progress.stop)
            self.root.after(0, self.status_var.set, f"送信完了: {to}")
            self.root.after(0, messagebox.showinfo, "完了", "メールを送信しました")
        except Exception as e:
            self.root.after(0, self.send_progress.stop)
            self.root.after(0, messagebox.showerror, "送信エラー", str(e))

    def _clear_compose(self):
        self.to_var.set("")
        self.cc_var.set("")
        self.subject_var.set("")
        self.send_body.delete("1.0", tk.END)

    def _test_connection(self):
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "SMTPサーバーを入力してください")
            return
        self.status_var.set("接続テスト中...")
        threading.Thread(target=self._do_test_connection, daemon=True).start()

    def _do_test_connection(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=10)
                smtp.ehlo()
                smtp.starttls()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=10)
            smtp.quit()
            self.root.after(0, self.status_var.set,
                            f"✅ SMTP接続成功: {host}:{port}")
        except Exception as e:
            self.root.after(0, self.status_var.set,
                            f"❌ SMTP接続失敗: {e}")

    def _fmt_size(self, size):
        if size < 1024:
            return f"{size}B"
        elif size < 1024 * 1024:
            return f"{size//1024}KB"
        return f"{size//1024//1024}MB"


if __name__ == "__main__":
    root = tk.Tk()
    app = App40(root)
    root.mainloop()

Entryウィジェットとイベントバインド

ttk.Entryで入力フィールドを作成します。bind('', ...)でEnterキー押下時に処理を実行できます。これにより、マウスを使わずキーボードだけで操作できるUXが実現できます。

import tkinter as tk
from tkinter import ttk, messagebox, scrolledtext
import smtplib
import imaplib
import email
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.header import decode_header
import threading
import os


class App40:
    """メールクライアント UI"""

    def __init__(self, root):
        self.root = root
        self.root.title("メールクライアント UI")
        self.root.geometry("1000x680")
        self.root.configure(bg="#f8f9fc")
        self._messages = []
        self._imap = None
        self._build_ui()

    def _build_ui(self):
        header = tk.Frame(self.root, bg="#1a237e", pady=8)
        header.pack(fill=tk.X)
        tk.Label(header, text="📧 メールクライアント UI",
                 font=("Noto Sans JP", 13, "bold"),
                 bg="#1a237e", fg="white").pack(side=tk.LEFT, padx=12)

        notebook = ttk.Notebook(self.root)
        notebook.pack(fill=tk.BOTH, expand=True, padx=6, pady=6)

        # ── 受信タブ ──────────────────────────────────────────────
        recv_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(recv_tab, text="📥 受信")
        self._build_recv_tab(recv_tab)

        # ── 送信タブ ──────────────────────────────────────────────
        send_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(send_tab, text="✉ 送信")
        self._build_send_tab(send_tab)

        # ── アカウント設定タブ ────────────────────────────────────
        settings_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(settings_tab, text="⚙ 設定")
        self._build_settings_tab(settings_tab)

        self.status_var = tk.StringVar(value="設定タブでアカウントを設定してください")
        tk.Label(self.root, textvariable=self.status_var,
                 bg="#dde", font=("Arial", 9), anchor="w", padx=8
                 ).pack(fill=tk.X, side=tk.BOTTOM)

    # ── 受信タブ ──────────────────────────────────────────────────

    def _build_recv_tab(self, parent):
        # ツールバー
        bar = tk.Frame(parent, bg="#f8f9fc")
        bar.pack(fill=tk.X, padx=8, pady=6)
        ttk.Button(bar, text="🔄 メールを取得",
                   command=self._fetch_mail).pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="フォルダ:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(12, 2))
        self.folder_var = tk.StringVar(value="INBOX")
        self.folder_cb = ttk.Combobox(bar, textvariable=self.folder_var,
                                       values=["INBOX", "Sent", "Drafts", "Trash"],
                                       width=14)
        self.folder_cb.pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="件数:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(8, 2))
        self.fetch_count_var = tk.IntVar(value=20)
        ttk.Spinbox(bar, from_=5, to=200,
                    textvariable=self.fetch_count_var, width=5).pack(side=tk.LEFT)

        # メール一覧 + 本文
        paned = ttk.PanedWindow(parent, orient=tk.VERTICAL)
        paned.pack(fill=tk.BOTH, expand=True, padx=8)

        # メール一覧
        list_f = tk.Frame(paned, bg="#f8f9fc")
        paned.add(list_f, weight=1)
        cols = ("from_", "subject", "date", "size")
        self.mail_tree = ttk.Treeview(list_f, columns=cols,
                                       show="headings", height=8)
        for c, h, w in [("from_", "差出人", 180), ("subject", "件名", 300),
                         ("date", "日時", 140), ("size", "サイズ", 70)]:
            self.mail_tree.heading(c, text=h)
            self.mail_tree.column(c, width=w, minwidth=40)
        sb = ttk.Scrollbar(list_f, command=self.mail_tree.yview)
        self.mail_tree.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.mail_tree.pack(fill=tk.BOTH, expand=True)
        self.mail_tree.bind("<<TreeviewSelect>>", self._on_mail_select)
        self.mail_tree.tag_configure("unread", font=("Arial", 10, "bold"))
        self.mail_tree.tag_configure("read", font=("Arial", 10))

        # 本文
        body_f = ttk.LabelFrame(paned, text="本文", padding=4)
        paned.add(body_f, weight=2)

        # ヘッダー情報
        self.mail_header_var = tk.StringVar(value="")
        tk.Label(body_f, textvariable=self.mail_header_var,
                 bg="#e8eaf6", fg="#283593", font=("Arial", 9),
                 anchor="w", padx=6).pack(fill=tk.X, pady=2)

        self.body_text = tk.Text(body_f, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  state=tk.DISABLED, wrap=tk.WORD)
        body_sb = ttk.Scrollbar(body_f, command=self.body_text.yview)
        self.body_text.configure(yscrollcommand=body_sb.set)
        body_sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.body_text.pack(fill=tk.BOTH, expand=True)

        # 返信ボタン
        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="↩ 返信",
                   command=self._reply).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 削除",
                   command=self._delete_mail).pack(side=tk.LEFT, padx=4)

        self.recv_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.recv_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 送信タブ ──────────────────────────────────────────────────

    def _build_send_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        for lbl, attr, show in [("宛先 (To):", "to_var", ""),
                                 ("CC:", "cc_var", ""),
                                 ("件名:", "subject_var", "")]:
            row = tk.Frame(parent, bg="#f8f9fc")
            row.pack(fill=tk.X, padx=8, pady=3)
            tk.Label(row, text=lbl, width=12, anchor="e", **lbl_s).pack(side=tk.LEFT)
            var = tk.StringVar()
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=60).pack(side=tk.LEFT, padx=4,
                                                              fill=tk.X, expand=True)

        # 本文
        tk.Label(parent, text="本文:", **lbl_s).pack(anchor="w", padx=8, pady=2)
        self.send_body = tk.Text(parent, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  height=16)
        sb = ttk.Scrollbar(parent, command=self.send_body.yview)
        self.send_body.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.send_body.pack(fill=tk.BOTH, expand=True, padx=8, pady=4)

        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="📤 送信",
                   command=self._send_mail).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 クリア",
                   command=self._clear_compose).pack(side=tk.LEFT, padx=4)

        self.send_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.send_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 設定タブ ──────────────────────────────────────────────────

    def _build_settings_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        # 送信 (SMTP)
        smtp_f = ttk.LabelFrame(parent, text="SMTP設定（送信）", padding=10)
        smtp_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("SMTPサーバー:", "smtp_host_var", "smtp.gmail.com", ""),
            ("ポート:", "smtp_port_var", "587", ""),
            ("ユーザー:", "smtp_user_var", "", ""),
            ("パスワード:", "smtp_pass_var", "", "*"),
        ]:
            row = tk.Frame(smtp_f, bg=smtp_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.smtp_tls_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(smtp_f, text="TLS/STARTTLS を使用",
                         variable=self.smtp_tls_var).pack(anchor="w")

        # 受信 (IMAP)
        imap_f = ttk.LabelFrame(parent, text="IMAP設定（受信）", padding=10)
        imap_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("IMAPサーバー:", "imap_host_var", "imap.gmail.com", ""),
            ("ポート:", "imap_port_var", "993", ""),
        ]:
            row = tk.Frame(imap_f, bg=imap_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.imap_ssl_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(imap_f, text="SSL を使用",
                         variable=self.imap_ssl_var).pack(anchor="w")

        # メモ
        tk.Label(parent,
                 text="※ Gmailの場合はアプリパスワードを使用してください。\n"
                      "  Google アカウント → セキュリティ → アプリパスワードで生成。",
                 bg="#fff3cd", fg="#856404", font=("Arial", 9),
                 anchor="w", padx=8, justify=tk.LEFT).pack(fill=tk.X, padx=8, pady=4)

        ttk.Button(parent, text="💾 設定を保存 / 接続テスト",
                   command=self._test_connection).pack(padx=8, pady=4)

    # ── メール操作 ────────────────────────────────────────────────

    def _fetch_mail(self):
        host = self.imap_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでIMAPサーバーを設定してください")
            return
        self.recv_progress.start(10)
        self.status_var.set("メール取得中...")
        threading.Thread(target=self._do_fetch_mail, daemon=True).start()

    def _do_fetch_mail(self):
        try:
            host = self.imap_host_var.get().strip()
            port = int(self.imap_port_var.get() or 993)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            folder = self.folder_var.get()
            count = self.fetch_count_var.get()

            if self.imap_ssl_var.get():
                imap = imaplib.IMAP4_SSL(host, port)
            else:
                imap = imaplib.IMAP4(host, port)

            imap.login(user, passwd)
            imap.select(folder)

            # 最新N件のIDを取得
            _, data = imap.search(None, "ALL")
            ids = data[0].split()
            fetch_ids = ids[-count:] if len(ids) >= count else ids
            fetch_ids = list(reversed(fetch_ids))

            messages = []
            for uid in fetch_ids:
                _, msg_data = imap.fetch(uid, "(RFC822.SIZE FLAGS RFC822.HEADER)")
                if not msg_data or not msg_data[0]:
                    continue
                raw_header = None
                size = 0
                flags = ""
                for part in msg_data:
                    if isinstance(part, tuple):
                        info = part[0].decode()
                        if "RFC822.SIZE" in info:
                            import re
                            m = re.search(r"RFC822\.SIZE (\d+)", info)
                            if m:
                                size = int(m.group(1))
                        if "FLAGS" in info:
                            flags = info
                        raw_header = part[1]
                if raw_header is None:
                    continue
                try:
                    msg = email.message_from_bytes(raw_header)
                    from_ = self._decode_header(msg.get("From", ""))
                    subject = self._decode_header(msg.get("Subject", ""))
                    date = msg.get("Date", "")[:25]
                    unread = "\\Seen" not in flags
                    messages.append({
                        "uid": uid,
                        "from": from_,
                        "subject": subject,
                        "date": date,
                        "size": size,
                        "unread": unread,
                    })
                except Exception:
                    pass

            self._imap = imap
            self._messages = messages
            self.root.after(0, self._show_mail_list, messages)
        except Exception as e:
            self.root.after(0, self.recv_progress.stop)
            self.root.after(0, self.status_var.set, f"取得エラー: {e}")

    def _show_mail_list(self, messages):
        self.recv_progress.stop()
        self.mail_tree.delete(*self.mail_tree.get_children())
        for msg in messages:
            tag = "unread" if msg.get("unread") else "read"
            self.mail_tree.insert("", "end",
                                   iid=str(msg["uid"]),
                                   values=(msg["from"][:30],
                                           msg["subject"][:60],
                                           msg["date"],
                                           self._fmt_size(msg["size"])),
                                   tags=(tag,))
        self.status_var.set(f"{len(messages)} 件取得")

    def _on_mail_select(self, event):
        sel = self.mail_tree.selection()
        if not sel or not self._imap:
            return
        uid = sel[0].encode()
        threading.Thread(target=self._load_mail_body,
                         args=(uid,), daemon=True).start()

    def _load_mail_body(self, uid):
        try:
            _, data = self._imap.fetch(uid, "(RFC822)")
            if not data or not data[0]:
                return
            raw = data[0][1]
            msg = email.message_from_bytes(raw)
            from_ = self._decode_header(msg.get("From", ""))
            subject = self._decode_header(msg.get("Subject", ""))
            date = msg.get("Date", "")
            body = self._extract_body(msg)
            self.root.after(0, self._show_body, from_, subject, date, body)
        except Exception as e:
            self.root.after(0, self.status_var.set, f"本文取得エラー: {e}")

    def _extract_body(self, msg):
        body = ""
        if msg.is_multipart():
            for part in msg.walk():
                ct = part.get_content_type()
                cd = str(part.get("Content-Disposition") or "")
                if ct == "text/plain" and "attachment" not in cd:
                    payload = part.get_payload(decode=True)
                    if payload:
                        charset = part.get_content_charset() or "utf-8"
                        body = payload.decode(charset, errors="replace")
                        break
        else:
            payload = msg.get_payload(decode=True)
            if payload:
                charset = msg.get_content_charset() or "utf-8"
                body = payload.decode(charset, errors="replace")
        return body

    def _show_body(self, from_, subject, date, body):
        self.mail_header_var.set(f"From: {from_}  |  件名: {subject}  |  日付: {date}")
        self.body_text.config(state=tk.NORMAL)
        self.body_text.delete("1.0", tk.END)
        self.body_text.insert("1.0", body)
        self.body_text.config(state=tk.DISABLED)

    def _decode_header(self, value):
        if not value:
            return ""
        parts = decode_header(value)
        decoded = []
        for part, enc in parts:
            if isinstance(part, bytes):
                decoded.append(part.decode(enc or "utf-8", errors="replace"))
            else:
                decoded.append(part)
        return "".join(decoded)

    def _reply(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        uid = sel[0]
        msg_data = next((m for m in self._messages if str(m["uid"]) == uid), None)
        if msg_data:
            self.to_var.set(msg_data.get("from", ""))
            self.subject_var.set("Re: " + msg_data.get("subject", ""))

    def _delete_mail(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        if messagebox.askyesno("確認", "選択したメールを削除しますか?") and self._imap:
            for uid in sel:
                try:
                    self._imap.store(uid.encode(), "+FLAGS", "\\Deleted")
                except Exception:
                    pass
            try:
                self._imap.expunge()
            except Exception:
                pass
            self._fetch_mail()

    # ── 送信 ─────────────────────────────────────────────────────

    def _send_mail(self):
        to = self.to_var.get().strip()
        if not to:
            messagebox.showwarning("警告", "宛先を入力してください")
            return
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでSMTPサーバーを設定してください")
            return
        self.send_progress.start(10)
        threading.Thread(target=self._do_send_mail, daemon=True).start()

    def _do_send_mail(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            to = self.to_var.get().strip()
            cc = self.cc_var.get().strip()
            subject = self.subject_var.get().strip()
            body = self.send_body.get("1.0", tk.END).strip()

            msg = MIMEMultipart("alternative")
            msg["From"] = user
            msg["To"] = to
            if cc:
                msg["Cc"] = cc
            msg["Subject"] = subject
            msg.attach(MIMEText(body, "plain", "utf-8"))

            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=15)
                smtp.ehlo()
                smtp.starttls()
                smtp.ehlo()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=15)

            smtp.login(user, passwd)
            recipients = [to] + ([cc] if cc else [])
            smtp.sendmail(user, recipients, msg.as_string())
            smtp.quit()

            self.root.after(0, self.send_progress.stop)
            self.root.after(0, self.status_var.set, f"送信完了: {to}")
            self.root.after(0, messagebox.showinfo, "完了", "メールを送信しました")
        except Exception as e:
            self.root.after(0, self.send_progress.stop)
            self.root.after(0, messagebox.showerror, "送信エラー", str(e))

    def _clear_compose(self):
        self.to_var.set("")
        self.cc_var.set("")
        self.subject_var.set("")
        self.send_body.delete("1.0", tk.END)

    def _test_connection(self):
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "SMTPサーバーを入力してください")
            return
        self.status_var.set("接続テスト中...")
        threading.Thread(target=self._do_test_connection, daemon=True).start()

    def _do_test_connection(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=10)
                smtp.ehlo()
                smtp.starttls()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=10)
            smtp.quit()
            self.root.after(0, self.status_var.set,
                            f"✅ SMTP接続成功: {host}:{port}")
        except Exception as e:
            self.root.after(0, self.status_var.set,
                            f"❌ SMTP接続失敗: {e}")

    def _fmt_size(self, size):
        if size < 1024:
            return f"{size}B"
        elif size < 1024 * 1024:
            return f"{size//1024}KB"
        return f"{size//1024//1024}MB"


if __name__ == "__main__":
    root = tk.Tk()
    app = App40(root)
    root.mainloop()

Textウィジェットでの結果表示

結果表示にはtk.Textウィジェットを使います。state=tk.DISABLEDでユーザーが直接編集できないようにし、表示前にNORMALに切り替えてからinsert()で内容を更新します。

import tkinter as tk
from tkinter import ttk, messagebox, scrolledtext
import smtplib
import imaplib
import email
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.header import decode_header
import threading
import os


class App40:
    """メールクライアント UI"""

    def __init__(self, root):
        self.root = root
        self.root.title("メールクライアント UI")
        self.root.geometry("1000x680")
        self.root.configure(bg="#f8f9fc")
        self._messages = []
        self._imap = None
        self._build_ui()

    def _build_ui(self):
        header = tk.Frame(self.root, bg="#1a237e", pady=8)
        header.pack(fill=tk.X)
        tk.Label(header, text="📧 メールクライアント UI",
                 font=("Noto Sans JP", 13, "bold"),
                 bg="#1a237e", fg="white").pack(side=tk.LEFT, padx=12)

        notebook = ttk.Notebook(self.root)
        notebook.pack(fill=tk.BOTH, expand=True, padx=6, pady=6)

        # ── 受信タブ ──────────────────────────────────────────────
        recv_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(recv_tab, text="📥 受信")
        self._build_recv_tab(recv_tab)

        # ── 送信タブ ──────────────────────────────────────────────
        send_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(send_tab, text="✉ 送信")
        self._build_send_tab(send_tab)

        # ── アカウント設定タブ ────────────────────────────────────
        settings_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(settings_tab, text="⚙ 設定")
        self._build_settings_tab(settings_tab)

        self.status_var = tk.StringVar(value="設定タブでアカウントを設定してください")
        tk.Label(self.root, textvariable=self.status_var,
                 bg="#dde", font=("Arial", 9), anchor="w", padx=8
                 ).pack(fill=tk.X, side=tk.BOTTOM)

    # ── 受信タブ ──────────────────────────────────────────────────

    def _build_recv_tab(self, parent):
        # ツールバー
        bar = tk.Frame(parent, bg="#f8f9fc")
        bar.pack(fill=tk.X, padx=8, pady=6)
        ttk.Button(bar, text="🔄 メールを取得",
                   command=self._fetch_mail).pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="フォルダ:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(12, 2))
        self.folder_var = tk.StringVar(value="INBOX")
        self.folder_cb = ttk.Combobox(bar, textvariable=self.folder_var,
                                       values=["INBOX", "Sent", "Drafts", "Trash"],
                                       width=14)
        self.folder_cb.pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="件数:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(8, 2))
        self.fetch_count_var = tk.IntVar(value=20)
        ttk.Spinbox(bar, from_=5, to=200,
                    textvariable=self.fetch_count_var, width=5).pack(side=tk.LEFT)

        # メール一覧 + 本文
        paned = ttk.PanedWindow(parent, orient=tk.VERTICAL)
        paned.pack(fill=tk.BOTH, expand=True, padx=8)

        # メール一覧
        list_f = tk.Frame(paned, bg="#f8f9fc")
        paned.add(list_f, weight=1)
        cols = ("from_", "subject", "date", "size")
        self.mail_tree = ttk.Treeview(list_f, columns=cols,
                                       show="headings", height=8)
        for c, h, w in [("from_", "差出人", 180), ("subject", "件名", 300),
                         ("date", "日時", 140), ("size", "サイズ", 70)]:
            self.mail_tree.heading(c, text=h)
            self.mail_tree.column(c, width=w, minwidth=40)
        sb = ttk.Scrollbar(list_f, command=self.mail_tree.yview)
        self.mail_tree.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.mail_tree.pack(fill=tk.BOTH, expand=True)
        self.mail_tree.bind("<<TreeviewSelect>>", self._on_mail_select)
        self.mail_tree.tag_configure("unread", font=("Arial", 10, "bold"))
        self.mail_tree.tag_configure("read", font=("Arial", 10))

        # 本文
        body_f = ttk.LabelFrame(paned, text="本文", padding=4)
        paned.add(body_f, weight=2)

        # ヘッダー情報
        self.mail_header_var = tk.StringVar(value="")
        tk.Label(body_f, textvariable=self.mail_header_var,
                 bg="#e8eaf6", fg="#283593", font=("Arial", 9),
                 anchor="w", padx=6).pack(fill=tk.X, pady=2)

        self.body_text = tk.Text(body_f, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  state=tk.DISABLED, wrap=tk.WORD)
        body_sb = ttk.Scrollbar(body_f, command=self.body_text.yview)
        self.body_text.configure(yscrollcommand=body_sb.set)
        body_sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.body_text.pack(fill=tk.BOTH, expand=True)

        # 返信ボタン
        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="↩ 返信",
                   command=self._reply).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 削除",
                   command=self._delete_mail).pack(side=tk.LEFT, padx=4)

        self.recv_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.recv_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 送信タブ ──────────────────────────────────────────────────

    def _build_send_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        for lbl, attr, show in [("宛先 (To):", "to_var", ""),
                                 ("CC:", "cc_var", ""),
                                 ("件名:", "subject_var", "")]:
            row = tk.Frame(parent, bg="#f8f9fc")
            row.pack(fill=tk.X, padx=8, pady=3)
            tk.Label(row, text=lbl, width=12, anchor="e", **lbl_s).pack(side=tk.LEFT)
            var = tk.StringVar()
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=60).pack(side=tk.LEFT, padx=4,
                                                              fill=tk.X, expand=True)

        # 本文
        tk.Label(parent, text="本文:", **lbl_s).pack(anchor="w", padx=8, pady=2)
        self.send_body = tk.Text(parent, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  height=16)
        sb = ttk.Scrollbar(parent, command=self.send_body.yview)
        self.send_body.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.send_body.pack(fill=tk.BOTH, expand=True, padx=8, pady=4)

        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="📤 送信",
                   command=self._send_mail).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 クリア",
                   command=self._clear_compose).pack(side=tk.LEFT, padx=4)

        self.send_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.send_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 設定タブ ──────────────────────────────────────────────────

    def _build_settings_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        # 送信 (SMTP)
        smtp_f = ttk.LabelFrame(parent, text="SMTP設定（送信）", padding=10)
        smtp_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("SMTPサーバー:", "smtp_host_var", "smtp.gmail.com", ""),
            ("ポート:", "smtp_port_var", "587", ""),
            ("ユーザー:", "smtp_user_var", "", ""),
            ("パスワード:", "smtp_pass_var", "", "*"),
        ]:
            row = tk.Frame(smtp_f, bg=smtp_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.smtp_tls_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(smtp_f, text="TLS/STARTTLS を使用",
                         variable=self.smtp_tls_var).pack(anchor="w")

        # 受信 (IMAP)
        imap_f = ttk.LabelFrame(parent, text="IMAP設定（受信）", padding=10)
        imap_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("IMAPサーバー:", "imap_host_var", "imap.gmail.com", ""),
            ("ポート:", "imap_port_var", "993", ""),
        ]:
            row = tk.Frame(imap_f, bg=imap_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.imap_ssl_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(imap_f, text="SSL を使用",
                         variable=self.imap_ssl_var).pack(anchor="w")

        # メモ
        tk.Label(parent,
                 text="※ Gmailの場合はアプリパスワードを使用してください。\n"
                      "  Google アカウント → セキュリティ → アプリパスワードで生成。",
                 bg="#fff3cd", fg="#856404", font=("Arial", 9),
                 anchor="w", padx=8, justify=tk.LEFT).pack(fill=tk.X, padx=8, pady=4)

        ttk.Button(parent, text="💾 設定を保存 / 接続テスト",
                   command=self._test_connection).pack(padx=8, pady=4)

    # ── メール操作 ────────────────────────────────────────────────

    def _fetch_mail(self):
        host = self.imap_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでIMAPサーバーを設定してください")
            return
        self.recv_progress.start(10)
        self.status_var.set("メール取得中...")
        threading.Thread(target=self._do_fetch_mail, daemon=True).start()

    def _do_fetch_mail(self):
        try:
            host = self.imap_host_var.get().strip()
            port = int(self.imap_port_var.get() or 993)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            folder = self.folder_var.get()
            count = self.fetch_count_var.get()

            if self.imap_ssl_var.get():
                imap = imaplib.IMAP4_SSL(host, port)
            else:
                imap = imaplib.IMAP4(host, port)

            imap.login(user, passwd)
            imap.select(folder)

            # 最新N件のIDを取得
            _, data = imap.search(None, "ALL")
            ids = data[0].split()
            fetch_ids = ids[-count:] if len(ids) >= count else ids
            fetch_ids = list(reversed(fetch_ids))

            messages = []
            for uid in fetch_ids:
                _, msg_data = imap.fetch(uid, "(RFC822.SIZE FLAGS RFC822.HEADER)")
                if not msg_data or not msg_data[0]:
                    continue
                raw_header = None
                size = 0
                flags = ""
                for part in msg_data:
                    if isinstance(part, tuple):
                        info = part[0].decode()
                        if "RFC822.SIZE" in info:
                            import re
                            m = re.search(r"RFC822\.SIZE (\d+)", info)
                            if m:
                                size = int(m.group(1))
                        if "FLAGS" in info:
                            flags = info
                        raw_header = part[1]
                if raw_header is None:
                    continue
                try:
                    msg = email.message_from_bytes(raw_header)
                    from_ = self._decode_header(msg.get("From", ""))
                    subject = self._decode_header(msg.get("Subject", ""))
                    date = msg.get("Date", "")[:25]
                    unread = "\\Seen" not in flags
                    messages.append({
                        "uid": uid,
                        "from": from_,
                        "subject": subject,
                        "date": date,
                        "size": size,
                        "unread": unread,
                    })
                except Exception:
                    pass

            self._imap = imap
            self._messages = messages
            self.root.after(0, self._show_mail_list, messages)
        except Exception as e:
            self.root.after(0, self.recv_progress.stop)
            self.root.after(0, self.status_var.set, f"取得エラー: {e}")

    def _show_mail_list(self, messages):
        self.recv_progress.stop()
        self.mail_tree.delete(*self.mail_tree.get_children())
        for msg in messages:
            tag = "unread" if msg.get("unread") else "read"
            self.mail_tree.insert("", "end",
                                   iid=str(msg["uid"]),
                                   values=(msg["from"][:30],
                                           msg["subject"][:60],
                                           msg["date"],
                                           self._fmt_size(msg["size"])),
                                   tags=(tag,))
        self.status_var.set(f"{len(messages)} 件取得")

    def _on_mail_select(self, event):
        sel = self.mail_tree.selection()
        if not sel or not self._imap:
            return
        uid = sel[0].encode()
        threading.Thread(target=self._load_mail_body,
                         args=(uid,), daemon=True).start()

    def _load_mail_body(self, uid):
        try:
            _, data = self._imap.fetch(uid, "(RFC822)")
            if not data or not data[0]:
                return
            raw = data[0][1]
            msg = email.message_from_bytes(raw)
            from_ = self._decode_header(msg.get("From", ""))
            subject = self._decode_header(msg.get("Subject", ""))
            date = msg.get("Date", "")
            body = self._extract_body(msg)
            self.root.after(0, self._show_body, from_, subject, date, body)
        except Exception as e:
            self.root.after(0, self.status_var.set, f"本文取得エラー: {e}")

    def _extract_body(self, msg):
        body = ""
        if msg.is_multipart():
            for part in msg.walk():
                ct = part.get_content_type()
                cd = str(part.get("Content-Disposition") or "")
                if ct == "text/plain" and "attachment" not in cd:
                    payload = part.get_payload(decode=True)
                    if payload:
                        charset = part.get_content_charset() or "utf-8"
                        body = payload.decode(charset, errors="replace")
                        break
        else:
            payload = msg.get_payload(decode=True)
            if payload:
                charset = msg.get_content_charset() or "utf-8"
                body = payload.decode(charset, errors="replace")
        return body

    def _show_body(self, from_, subject, date, body):
        self.mail_header_var.set(f"From: {from_}  |  件名: {subject}  |  日付: {date}")
        self.body_text.config(state=tk.NORMAL)
        self.body_text.delete("1.0", tk.END)
        self.body_text.insert("1.0", body)
        self.body_text.config(state=tk.DISABLED)

    def _decode_header(self, value):
        if not value:
            return ""
        parts = decode_header(value)
        decoded = []
        for part, enc in parts:
            if isinstance(part, bytes):
                decoded.append(part.decode(enc or "utf-8", errors="replace"))
            else:
                decoded.append(part)
        return "".join(decoded)

    def _reply(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        uid = sel[0]
        msg_data = next((m for m in self._messages if str(m["uid"]) == uid), None)
        if msg_data:
            self.to_var.set(msg_data.get("from", ""))
            self.subject_var.set("Re: " + msg_data.get("subject", ""))

    def _delete_mail(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        if messagebox.askyesno("確認", "選択したメールを削除しますか?") and self._imap:
            for uid in sel:
                try:
                    self._imap.store(uid.encode(), "+FLAGS", "\\Deleted")
                except Exception:
                    pass
            try:
                self._imap.expunge()
            except Exception:
                pass
            self._fetch_mail()

    # ── 送信 ─────────────────────────────────────────────────────

    def _send_mail(self):
        to = self.to_var.get().strip()
        if not to:
            messagebox.showwarning("警告", "宛先を入力してください")
            return
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでSMTPサーバーを設定してください")
            return
        self.send_progress.start(10)
        threading.Thread(target=self._do_send_mail, daemon=True).start()

    def _do_send_mail(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            to = self.to_var.get().strip()
            cc = self.cc_var.get().strip()
            subject = self.subject_var.get().strip()
            body = self.send_body.get("1.0", tk.END).strip()

            msg = MIMEMultipart("alternative")
            msg["From"] = user
            msg["To"] = to
            if cc:
                msg["Cc"] = cc
            msg["Subject"] = subject
            msg.attach(MIMEText(body, "plain", "utf-8"))

            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=15)
                smtp.ehlo()
                smtp.starttls()
                smtp.ehlo()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=15)

            smtp.login(user, passwd)
            recipients = [to] + ([cc] if cc else [])
            smtp.sendmail(user, recipients, msg.as_string())
            smtp.quit()

            self.root.after(0, self.send_progress.stop)
            self.root.after(0, self.status_var.set, f"送信完了: {to}")
            self.root.after(0, messagebox.showinfo, "完了", "メールを送信しました")
        except Exception as e:
            self.root.after(0, self.send_progress.stop)
            self.root.after(0, messagebox.showerror, "送信エラー", str(e))

    def _clear_compose(self):
        self.to_var.set("")
        self.cc_var.set("")
        self.subject_var.set("")
        self.send_body.delete("1.0", tk.END)

    def _test_connection(self):
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "SMTPサーバーを入力してください")
            return
        self.status_var.set("接続テスト中...")
        threading.Thread(target=self._do_test_connection, daemon=True).start()

    def _do_test_connection(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=10)
                smtp.ehlo()
                smtp.starttls()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=10)
            smtp.quit()
            self.root.after(0, self.status_var.set,
                            f"✅ SMTP接続成功: {host}:{port}")
        except Exception as e:
            self.root.after(0, self.status_var.set,
                            f"❌ SMTP接続失敗: {e}")

    def _fmt_size(self, size):
        if size < 1024:
            return f"{size}B"
        elif size < 1024 * 1024:
            return f"{size//1024}KB"
        return f"{size//1024//1024}MB"


if __name__ == "__main__":
    root = tk.Tk()
    app = App40(root)
    root.mainloop()

例外処理とmessagebox

try-except で ValueError と Exception を捕捉し、messagebox.showerror() でユーザーにわかりやすいエラーメッセージを表示します。入力バリデーションは必ず実装しましょう。

import tkinter as tk
from tkinter import ttk, messagebox, scrolledtext
import smtplib
import imaplib
import email
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.header import decode_header
import threading
import os


class App40:
    """メールクライアント UI"""

    def __init__(self, root):
        self.root = root
        self.root.title("メールクライアント UI")
        self.root.geometry("1000x680")
        self.root.configure(bg="#f8f9fc")
        self._messages = []
        self._imap = None
        self._build_ui()

    def _build_ui(self):
        header = tk.Frame(self.root, bg="#1a237e", pady=8)
        header.pack(fill=tk.X)
        tk.Label(header, text="📧 メールクライアント UI",
                 font=("Noto Sans JP", 13, "bold"),
                 bg="#1a237e", fg="white").pack(side=tk.LEFT, padx=12)

        notebook = ttk.Notebook(self.root)
        notebook.pack(fill=tk.BOTH, expand=True, padx=6, pady=6)

        # ── 受信タブ ──────────────────────────────────────────────
        recv_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(recv_tab, text="📥 受信")
        self._build_recv_tab(recv_tab)

        # ── 送信タブ ──────────────────────────────────────────────
        send_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(send_tab, text="✉ 送信")
        self._build_send_tab(send_tab)

        # ── アカウント設定タブ ────────────────────────────────────
        settings_tab = tk.Frame(notebook, bg="#f8f9fc")
        notebook.add(settings_tab, text="⚙ 設定")
        self._build_settings_tab(settings_tab)

        self.status_var = tk.StringVar(value="設定タブでアカウントを設定してください")
        tk.Label(self.root, textvariable=self.status_var,
                 bg="#dde", font=("Arial", 9), anchor="w", padx=8
                 ).pack(fill=tk.X, side=tk.BOTTOM)

    # ── 受信タブ ──────────────────────────────────────────────────

    def _build_recv_tab(self, parent):
        # ツールバー
        bar = tk.Frame(parent, bg="#f8f9fc")
        bar.pack(fill=tk.X, padx=8, pady=6)
        ttk.Button(bar, text="🔄 メールを取得",
                   command=self._fetch_mail).pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="フォルダ:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(12, 2))
        self.folder_var = tk.StringVar(value="INBOX")
        self.folder_cb = ttk.Combobox(bar, textvariable=self.folder_var,
                                       values=["INBOX", "Sent", "Drafts", "Trash"],
                                       width=14)
        self.folder_cb.pack(side=tk.LEFT, padx=4)
        tk.Label(bar, text="件数:", bg="#f8f9fc",
                 font=("Arial", 9)).pack(side=tk.LEFT, padx=(8, 2))
        self.fetch_count_var = tk.IntVar(value=20)
        ttk.Spinbox(bar, from_=5, to=200,
                    textvariable=self.fetch_count_var, width=5).pack(side=tk.LEFT)

        # メール一覧 + 本文
        paned = ttk.PanedWindow(parent, orient=tk.VERTICAL)
        paned.pack(fill=tk.BOTH, expand=True, padx=8)

        # メール一覧
        list_f = tk.Frame(paned, bg="#f8f9fc")
        paned.add(list_f, weight=1)
        cols = ("from_", "subject", "date", "size")
        self.mail_tree = ttk.Treeview(list_f, columns=cols,
                                       show="headings", height=8)
        for c, h, w in [("from_", "差出人", 180), ("subject", "件名", 300),
                         ("date", "日時", 140), ("size", "サイズ", 70)]:
            self.mail_tree.heading(c, text=h)
            self.mail_tree.column(c, width=w, minwidth=40)
        sb = ttk.Scrollbar(list_f, command=self.mail_tree.yview)
        self.mail_tree.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.mail_tree.pack(fill=tk.BOTH, expand=True)
        self.mail_tree.bind("<<TreeviewSelect>>", self._on_mail_select)
        self.mail_tree.tag_configure("unread", font=("Arial", 10, "bold"))
        self.mail_tree.tag_configure("read", font=("Arial", 10))

        # 本文
        body_f = ttk.LabelFrame(paned, text="本文", padding=4)
        paned.add(body_f, weight=2)

        # ヘッダー情報
        self.mail_header_var = tk.StringVar(value="")
        tk.Label(body_f, textvariable=self.mail_header_var,
                 bg="#e8eaf6", fg="#283593", font=("Arial", 9),
                 anchor="w", padx=6).pack(fill=tk.X, pady=2)

        self.body_text = tk.Text(body_f, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  state=tk.DISABLED, wrap=tk.WORD)
        body_sb = ttk.Scrollbar(body_f, command=self.body_text.yview)
        self.body_text.configure(yscrollcommand=body_sb.set)
        body_sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.body_text.pack(fill=tk.BOTH, expand=True)

        # 返信ボタン
        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="↩ 返信",
                   command=self._reply).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 削除",
                   command=self._delete_mail).pack(side=tk.LEFT, padx=4)

        self.recv_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.recv_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 送信タブ ──────────────────────────────────────────────────

    def _build_send_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        for lbl, attr, show in [("宛先 (To):", "to_var", ""),
                                 ("CC:", "cc_var", ""),
                                 ("件名:", "subject_var", "")]:
            row = tk.Frame(parent, bg="#f8f9fc")
            row.pack(fill=tk.X, padx=8, pady=3)
            tk.Label(row, text=lbl, width=12, anchor="e", **lbl_s).pack(side=tk.LEFT)
            var = tk.StringVar()
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=60).pack(side=tk.LEFT, padx=4,
                                                              fill=tk.X, expand=True)

        # 本文
        tk.Label(parent, text="本文:", **lbl_s).pack(anchor="w", padx=8, pady=2)
        self.send_body = tk.Text(parent, bg="#ffffff", fg="#333",
                                  font=("Arial", 11), relief=tk.FLAT,
                                  height=16)
        sb = ttk.Scrollbar(parent, command=self.send_body.yview)
        self.send_body.configure(yscrollcommand=sb.set)
        sb.pack(side=tk.RIGHT, fill=tk.Y)
        self.send_body.pack(fill=tk.BOTH, expand=True, padx=8, pady=4)

        btn_f = tk.Frame(parent, bg="#f8f9fc")
        btn_f.pack(fill=tk.X, padx=8, pady=4)
        ttk.Button(btn_f, text="📤 送信",
                   command=self._send_mail).pack(side=tk.LEFT, padx=4)
        ttk.Button(btn_f, text="🗑 クリア",
                   command=self._clear_compose).pack(side=tk.LEFT, padx=4)

        self.send_progress = ttk.Progressbar(parent, mode="indeterminate")
        self.send_progress.pack(fill=tk.X, padx=8, pady=2)

    # ── 設定タブ ──────────────────────────────────────────────────

    def _build_settings_tab(self, parent):
        lbl_s = {"bg": "#f8f9fc", "font": ("Arial", 10)}

        # 送信 (SMTP)
        smtp_f = ttk.LabelFrame(parent, text="SMTP設定（送信）", padding=10)
        smtp_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("SMTPサーバー:", "smtp_host_var", "smtp.gmail.com", ""),
            ("ポート:", "smtp_port_var", "587", ""),
            ("ユーザー:", "smtp_user_var", "", ""),
            ("パスワード:", "smtp_pass_var", "", "*"),
        ]:
            row = tk.Frame(smtp_f, bg=smtp_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.smtp_tls_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(smtp_f, text="TLS/STARTTLS を使用",
                         variable=self.smtp_tls_var).pack(anchor="w")

        # 受信 (IMAP)
        imap_f = ttk.LabelFrame(parent, text="IMAP設定（受信）", padding=10)
        imap_f.pack(fill=tk.X, padx=8, pady=6)
        for lbl, attr, val, show in [
            ("IMAPサーバー:", "imap_host_var", "imap.gmail.com", ""),
            ("ポート:", "imap_port_var", "993", ""),
        ]:
            row = tk.Frame(imap_f, bg=imap_f.cget("background"))
            row.pack(fill=tk.X, pady=2)
            tk.Label(row, text=lbl, width=16, anchor="e",
                     bg=row.cget("bg"),
                     font=("Arial", 10)).pack(side=tk.LEFT)
            var = tk.StringVar(value=val)
            setattr(self, attr, var)
            ttk.Entry(row, textvariable=var, width=34, show=show).pack(side=tk.LEFT, padx=4)

        self.imap_ssl_var = tk.BooleanVar(value=True)
        ttk.Checkbutton(imap_f, text="SSL を使用",
                         variable=self.imap_ssl_var).pack(anchor="w")

        # メモ
        tk.Label(parent,
                 text="※ Gmailの場合はアプリパスワードを使用してください。\n"
                      "  Google アカウント → セキュリティ → アプリパスワードで生成。",
                 bg="#fff3cd", fg="#856404", font=("Arial", 9),
                 anchor="w", padx=8, justify=tk.LEFT).pack(fill=tk.X, padx=8, pady=4)

        ttk.Button(parent, text="💾 設定を保存 / 接続テスト",
                   command=self._test_connection).pack(padx=8, pady=4)

    # ── メール操作 ────────────────────────────────────────────────

    def _fetch_mail(self):
        host = self.imap_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでIMAPサーバーを設定してください")
            return
        self.recv_progress.start(10)
        self.status_var.set("メール取得中...")
        threading.Thread(target=self._do_fetch_mail, daemon=True).start()

    def _do_fetch_mail(self):
        try:
            host = self.imap_host_var.get().strip()
            port = int(self.imap_port_var.get() or 993)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            folder = self.folder_var.get()
            count = self.fetch_count_var.get()

            if self.imap_ssl_var.get():
                imap = imaplib.IMAP4_SSL(host, port)
            else:
                imap = imaplib.IMAP4(host, port)

            imap.login(user, passwd)
            imap.select(folder)

            # 最新N件のIDを取得
            _, data = imap.search(None, "ALL")
            ids = data[0].split()
            fetch_ids = ids[-count:] if len(ids) >= count else ids
            fetch_ids = list(reversed(fetch_ids))

            messages = []
            for uid in fetch_ids:
                _, msg_data = imap.fetch(uid, "(RFC822.SIZE FLAGS RFC822.HEADER)")
                if not msg_data or not msg_data[0]:
                    continue
                raw_header = None
                size = 0
                flags = ""
                for part in msg_data:
                    if isinstance(part, tuple):
                        info = part[0].decode()
                        if "RFC822.SIZE" in info:
                            import re
                            m = re.search(r"RFC822\.SIZE (\d+)", info)
                            if m:
                                size = int(m.group(1))
                        if "FLAGS" in info:
                            flags = info
                        raw_header = part[1]
                if raw_header is None:
                    continue
                try:
                    msg = email.message_from_bytes(raw_header)
                    from_ = self._decode_header(msg.get("From", ""))
                    subject = self._decode_header(msg.get("Subject", ""))
                    date = msg.get("Date", "")[:25]
                    unread = "\\Seen" not in flags
                    messages.append({
                        "uid": uid,
                        "from": from_,
                        "subject": subject,
                        "date": date,
                        "size": size,
                        "unread": unread,
                    })
                except Exception:
                    pass

            self._imap = imap
            self._messages = messages
            self.root.after(0, self._show_mail_list, messages)
        except Exception as e:
            self.root.after(0, self.recv_progress.stop)
            self.root.after(0, self.status_var.set, f"取得エラー: {e}")

    def _show_mail_list(self, messages):
        self.recv_progress.stop()
        self.mail_tree.delete(*self.mail_tree.get_children())
        for msg in messages:
            tag = "unread" if msg.get("unread") else "read"
            self.mail_tree.insert("", "end",
                                   iid=str(msg["uid"]),
                                   values=(msg["from"][:30],
                                           msg["subject"][:60],
                                           msg["date"],
                                           self._fmt_size(msg["size"])),
                                   tags=(tag,))
        self.status_var.set(f"{len(messages)} 件取得")

    def _on_mail_select(self, event):
        sel = self.mail_tree.selection()
        if not sel or not self._imap:
            return
        uid = sel[0].encode()
        threading.Thread(target=self._load_mail_body,
                         args=(uid,), daemon=True).start()

    def _load_mail_body(self, uid):
        try:
            _, data = self._imap.fetch(uid, "(RFC822)")
            if not data or not data[0]:
                return
            raw = data[0][1]
            msg = email.message_from_bytes(raw)
            from_ = self._decode_header(msg.get("From", ""))
            subject = self._decode_header(msg.get("Subject", ""))
            date = msg.get("Date", "")
            body = self._extract_body(msg)
            self.root.after(0, self._show_body, from_, subject, date, body)
        except Exception as e:
            self.root.after(0, self.status_var.set, f"本文取得エラー: {e}")

    def _extract_body(self, msg):
        body = ""
        if msg.is_multipart():
            for part in msg.walk():
                ct = part.get_content_type()
                cd = str(part.get("Content-Disposition") or "")
                if ct == "text/plain" and "attachment" not in cd:
                    payload = part.get_payload(decode=True)
                    if payload:
                        charset = part.get_content_charset() or "utf-8"
                        body = payload.decode(charset, errors="replace")
                        break
        else:
            payload = msg.get_payload(decode=True)
            if payload:
                charset = msg.get_content_charset() or "utf-8"
                body = payload.decode(charset, errors="replace")
        return body

    def _show_body(self, from_, subject, date, body):
        self.mail_header_var.set(f"From: {from_}  |  件名: {subject}  |  日付: {date}")
        self.body_text.config(state=tk.NORMAL)
        self.body_text.delete("1.0", tk.END)
        self.body_text.insert("1.0", body)
        self.body_text.config(state=tk.DISABLED)

    def _decode_header(self, value):
        if not value:
            return ""
        parts = decode_header(value)
        decoded = []
        for part, enc in parts:
            if isinstance(part, bytes):
                decoded.append(part.decode(enc or "utf-8", errors="replace"))
            else:
                decoded.append(part)
        return "".join(decoded)

    def _reply(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        uid = sel[0]
        msg_data = next((m for m in self._messages if str(m["uid"]) == uid), None)
        if msg_data:
            self.to_var.set(msg_data.get("from", ""))
            self.subject_var.set("Re: " + msg_data.get("subject", ""))

    def _delete_mail(self):
        sel = self.mail_tree.selection()
        if not sel:
            return
        if messagebox.askyesno("確認", "選択したメールを削除しますか?") and self._imap:
            for uid in sel:
                try:
                    self._imap.store(uid.encode(), "+FLAGS", "\\Deleted")
                except Exception:
                    pass
            try:
                self._imap.expunge()
            except Exception:
                pass
            self._fetch_mail()

    # ── 送信 ─────────────────────────────────────────────────────

    def _send_mail(self):
        to = self.to_var.get().strip()
        if not to:
            messagebox.showwarning("警告", "宛先を入力してください")
            return
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "設定タブでSMTPサーバーを設定してください")
            return
        self.send_progress.start(10)
        threading.Thread(target=self._do_send_mail, daemon=True).start()

    def _do_send_mail(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            user = self.smtp_user_var.get().strip()
            passwd = self.smtp_pass_var.get()
            to = self.to_var.get().strip()
            cc = self.cc_var.get().strip()
            subject = self.subject_var.get().strip()
            body = self.send_body.get("1.0", tk.END).strip()

            msg = MIMEMultipart("alternative")
            msg["From"] = user
            msg["To"] = to
            if cc:
                msg["Cc"] = cc
            msg["Subject"] = subject
            msg.attach(MIMEText(body, "plain", "utf-8"))

            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=15)
                smtp.ehlo()
                smtp.starttls()
                smtp.ehlo()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=15)

            smtp.login(user, passwd)
            recipients = [to] + ([cc] if cc else [])
            smtp.sendmail(user, recipients, msg.as_string())
            smtp.quit()

            self.root.after(0, self.send_progress.stop)
            self.root.after(0, self.status_var.set, f"送信完了: {to}")
            self.root.after(0, messagebox.showinfo, "完了", "メールを送信しました")
        except Exception as e:
            self.root.after(0, self.send_progress.stop)
            self.root.after(0, messagebox.showerror, "送信エラー", str(e))

    def _clear_compose(self):
        self.to_var.set("")
        self.cc_var.set("")
        self.subject_var.set("")
        self.send_body.delete("1.0", tk.END)

    def _test_connection(self):
        host = self.smtp_host_var.get().strip()
        if not host:
            messagebox.showwarning("警告", "SMTPサーバーを入力してください")
            return
        self.status_var.set("接続テスト中...")
        threading.Thread(target=self._do_test_connection, daemon=True).start()

    def _do_test_connection(self):
        try:
            host = self.smtp_host_var.get().strip()
            port = int(self.smtp_port_var.get() or 587)
            if self.smtp_tls_var.get():
                smtp = smtplib.SMTP(host, port, timeout=10)
                smtp.ehlo()
                smtp.starttls()
            else:
                smtp = smtplib.SMTP_SSL(host, port, timeout=10)
            smtp.quit()
            self.root.after(0, self.status_var.set,
                            f"✅ SMTP接続成功: {host}:{port}")
        except Exception as e:
            self.root.after(0, self.status_var.set,
                            f"❌ SMTP接続失敗: {e}")

    def _fmt_size(self, size):
        if size < 1024:
            return f"{size}B"
        elif size < 1024 * 1024:
            return f"{size//1024}KB"
        return f"{size//1024//1024}MB"


if __name__ == "__main__":
    root = tk.Tk()
    app = App40(root)
    root.mainloop()

💡 ダークモードを追加する

bg色・fg色を辞書で管理し、ボタン1つでダークモード・ライトモードを切り替えられるようにしましょう。

💡 データのエクスポート機能

計算結果をCSV・TXTファイルに保存するエクスポート機能を追加しましょう。filedialog.asksaveasfilename()でファイル保存ダイアログが使えます。

💡 入力履歴機能

以前の入力値を覚えておいてComboboxのドロップダウンで再選択できる履歴機能を追加しましょう。

❌ 日本語フォントが表示されない

原因：システムに日本語フォントが見つからない場合があります。

解決法：font引数を省略するかシステムに合ったフォントを指定してください。

❌ ウィンドウのサイズが変更できない

原因：resizable(False, False)が設定されています。

解決法：resizable(True, True)に変更してください。