gh-59396: Use themed widgets in tkinter.filedialog

The FileDialog, LoadFileDialog and SaveFileDialog dialogs are now built from
the themed tkinter.ttk widgets by default instead of the classic tkinter
widgets, and gained a use_ttk parameter that selects between the classic Tk
widgets and the themed ttk widgets.

They were also brought closer to the native Tk file dialog: the buttons and
field labels gained Alt key accelerators, the default ring follows the keyboard
focus, the Escape key cancels the dialog, the focus traverses the widgets in
their visual order, and the directory and file lists gained a horizontal
scrollbar and type-ahead selection.  The dialog is now transient and centered
over its parent, and the SaveFileDialog overwrite confirmation uses a themed
message box.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: serhiy-storchaka

Doc/library/dialog.rst

@@ -216,9 +216,19 @@ These do not emulate the native look-and-feel of the platform.
 .. note::  The *FileDialog* class should be subclassed for custom event
    handling and behaviour.
 
-.. class:: FileDialog(master, title=None)
+.. class:: FileDialog(master, title=None, *, use_ttk=True)
 
    Create a basic file selection dialog.
+   Its layout -- a filter entry, side-by-side directory and file lists, and a
+   selection entry -- follows the classic Motif file selection dialog.
+   When *use_ttk* is true (the default), the dialog is built from the themed
+   :mod:`tkinter.ttk` widgets; when false, from the classic :mod:`tkinter`
+   widgets.
+
+   .. versionchanged:: next
+      The dialog is now built from the themed :mod:`tkinter.ttk` widgets by
+      default, instead of the classic :mod:`tkinter` widgets.
+      Added the *use_ttk* parameter.
 
    .. method:: cancel_command(event=None)
 
@@ -280,21 +290,27 @@ These do not emulate the native look-and-feel of the platform.
       Update the current file selection to *file*.
 
 
-.. class:: LoadFileDialog(master, title=None)
+.. class:: LoadFileDialog(master, title=None, *, use_ttk=True)
 
    A subclass of FileDialog that creates a dialog window for selecting an
    existing file.
 
+   .. versionchanged:: next
+      Added the *use_ttk* parameter.
+
    .. method:: ok_command()
 
       Test that a file is provided and that the selection indicates an
       already existing file.
 
-.. class:: SaveFileDialog(master, title=None)
+.. class:: SaveFileDialog(master, title=None, *, use_ttk=True)
 
    A subclass of FileDialog that creates a dialog window for selecting a
    destination file.
 
+   .. versionchanged:: next
+      Added the *use_ttk* parameter.
+
    .. method:: ok_command()
 
       Test whether or not the selection points to a valid file that is not a

Doc/whatsnew/3.16.rst

@@ -236,6 +236,14 @@ tkinter
   ttk version, and accepts mappings of button options as *buttons* entries.
   (Contributed by Serhiy Storchaka in :gh:`59396`.)
 
+* The :class:`!tkinter.filedialog.FileDialog` dialog and its
+  :class:`!tkinter.filedialog.LoadFileDialog` and
+  :class:`!tkinter.filedialog.SaveFileDialog` subclasses are now built from the
+  themed :mod:`tkinter.ttk` widgets by default instead of the classic
+  :mod:`tkinter` widgets, and gained a *use_ttk* parameter to select between
+  them.
+  (Contributed by Serhiy Storchaka in :gh:`59396`.)
+
 xml
 ---
 

Lib/test/test_tkinter/test_filedialog.py

@@ -1,6 +1,8 @@
 import os
 import unittest
+import tkinter
 from tkinter import filedialog
+from tkinter import ttk
 from tkinter.commondialog import Dialog
 from test.support import requires, swap_attr
 from test.test_tkinter.support import setUpModule  # noqa: F401
@@ -68,6 +70,104 @@ def test_subclasses(self):
                 self.assertIsInstance(d, filedialog.FileDialog)
                 self.assertEqual(d.top.title(), cls.title)
 
+    # --- Themed widgets and keyboard (modernization) ---
+
+    def open(self, **kw):
+        d = filedialog.FileDialog(self.root, **kw)
+        self.addCleanup(lambda: d.top.winfo_exists() and d.top.destroy())
+        d.top.deiconify()  # __init__ leaves the dialog withdrawn until go()
+        d.top.update()
+        return d
+
+    def test_use_ttk(self):
+        # The dialog uses the themed (ttk) widgets by default.
+        d = self.open()
+        self.assertEqual(d.ok_button.winfo_class(), 'TButton')
+        self.assertEqual(d.selection.winfo_class(), 'TEntry')
+
+    def test_use_classic(self):
+        # use_ttk=False uses the classic Tk widgets.
+        d = self.open(use_ttk=False)
+        self.assertEqual(d.ok_button.winfo_class(), 'Button')
+        self.assertEqual(d.selection.winfo_class(), 'Entry')
+        if d.top._windowingsystem == 'x11':
+            self.assertEqual(str(d.botframe.cget('relief')), 'raised')
+
+    def test_background(self):
+        # The ttk dialog adopts the ttk background, even a customized one, while
+        # the classic dialog keeps the default Toplevel background.
+        style = ttk.Style(self.root)
+        old = style.lookup('.', 'background')
+        style.configure('.', background='#123456')
+        self.addCleanup(style.configure, '.', background=old)
+        d = self.open()
+        self.assertEqual(str(d.top.cget('background')), '#123456')
+        d = self.open(use_ttk=False)
+        ref = tkinter.Toplevel(self.root)
+        self.addCleanup(ref.destroy)
+        self.assertEqual(str(d.top.cget('background')),
+                         str(ref.cget('background')))
+
+    def test_button_accelerator(self):
+        # The buttons' "&" accelerators are parsed.
+        d = self.open()
+        self.assertEqual(str(d.ok_button.cget('text')), 'OK')
+        self.assertEqual(int(d.ok_button.cget('underline')), 0)
+
+    def test_default_ring(self):
+        # The default ring follows the keyboard focus among the buttons.
+        d = self.open()
+        self.assertEqual(str(d.cancel_button.cget('default')), 'normal')
+        d.cancel_button.focus_force()
+        d.top.update()
+        self.assertEqual(str(d.cancel_button.cget('default')), 'active')
+        d.ok_button.focus_force()
+        d.top.update()
+        self.assertEqual(str(d.cancel_button.cget('default')), 'normal')
+
+    def test_alt_key(self):
+        # Alt + the underlined letter invokes the matching button.
+        d = self.open()
+        invoked = []
+        d.cancel_button.configure(command=lambda: invoked.append(True))
+        d.top.focus_force()
+        d.top.update()
+        d.top.event_generate('<Alt-c>')  # "&Cancel"
+        d.top.update()
+        self.assertTrue(invoked)
+
+    def test_escape_cancels(self):
+        # The Escape key cancels the dialog.
+        d = self.open()
+        d.how = 'spam'
+        d.top.focus_force()
+        d.top.update()
+        d.top.event_generate('<Escape>')
+        d.top.update()
+        self.assertIsNone(d.how)
+
+    def test_horizontal_scrollbars(self):
+        # Each list has a horizontal scrollbar besides the vertical one.
+        d = self.open()
+        self.assertEqual(str(d.dirshbar.cget('orient')), 'horizontal')
+        self.assertEqual(str(d.fileshbar.cget('orient')), 'horizontal')
+        self.assertTrue(d.dirs.cget('xscrollcommand'))
+        self.assertTrue(d.files.cget('xscrollcommand'))
+
+    def test_type_ahead(self):
+        # Typing characters over a list jumps to a matching entry.
+        d = self.open()
+        d.directory = os.getcwd()  # browsing the match fills the selection entry
+        d.files.delete(0, 'end')
+        for name in ('alpha', 'bravo', 'charlie'):
+            d.files.insert('end', name)
+        d.files.focus_force()
+        d.top.update()
+        d.files.event_generate('<Key>', keysym='c')
+        d.top.update()
+        sel = d.files.curselection()
+        self.assertEqual([d.files.get(i) for i in sel], ['charlie'])
+
 
 if __name__ == "__main__":
     unittest.main()