gh-59396: Modernize tkinter.simpledialog (GH-151848)

Rework SimpleDialog and Dialog to match the look and feel of the native Tk
dialogs ::tk_dialog and ::tk::MessageBox.

* SimpleDialog is a Python port of ::tk_dialog and Dialog a base class
  modelled on ::tk::MessageBox.  Both adopt the message-box keyboard
  conventions: button accelerators, a default ring that follows the keyboard
  focus, and a <Return> binding that invokes the focused button.
* Both classes gain a use_ttk parameter that selects the classic Tk or the
  themed ttk widgets.  It controls the widget set and the appearance that the
  two procedures style differently, but not the keyboard behaviour.
* Update _place_window with the Tk 9.1 placement refinements.
* The new helpers _temp_grab_focus (a modal grab/focus context manager),
  _underline_ampersand and _find_alt_key_target (ports of the Tk
  accelerator-key procedures) can be reused by other tkinter dialogs, as
  _setup_dialog already is.
* Fix several defects uncovered while comparing with the Tcl sources.
* Improve the simpledialog demo.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: serhiy-storchaka

Doc/library/dialog.rst

@@ -15,9 +15,9 @@ The :mod:`!tkinter.simpledialog` module contains convenience classes and
 functions for creating simple modal dialogs to get a value from the user.
 
 
-.. function:: askfloat(title, prompt, *, initialvalue=None, minvalue=None, maxvalue=None, parent=None)
-              askinteger(title, prompt, *, initialvalue=None, minvalue=None, maxvalue=None, parent=None)
-              askstring(title, prompt, *, initialvalue=None, show=None, parent=None)
+.. function:: askfloat(title, prompt, *, initialvalue=None, minvalue=None, maxvalue=None, parent=None, use_ttk=True)
+              askinteger(title, prompt, *, initialvalue=None, minvalue=None, maxvalue=None, parent=None, use_ttk=True)
+              askstring(title, prompt, *, initialvalue=None, show=None, parent=None, use_ttk=True)
 
    Prompt the user to enter a value of the desired type and return it, or
    ``None`` if the dialog is cancelled.
@@ -29,12 +29,22 @@ functions for creating simple modal dialogs to get a value from the user.
    *maxvalue*, which bound the accepted value.
    :func:`askstring` also accepts *show*, a character used to mask the entered
    text, for example ``'*'`` to hide a password.
+   They use the themed :mod:`tkinter.ttk` widgets; pass ``use_ttk=False`` for
+   the classic widgets.
 
-.. class:: Dialog(parent, title=None)
+.. class:: Dialog(parent, title=None, *, use_ttk=False)
 
    The base class for custom dialogs.
    Instantiating it shows the dialog modally and returns once the user closes
    it; the entered value is then available in the :attr:`!result` attribute.
+   When *use_ttk* is false (the default), the dialog is built from the classic
+   :mod:`tkinter` widgets, modelled on the classic ``tk_dialog``; when true,
+   from the themed :mod:`tkinter.ttk` widgets, modelled on the Tk message box.
+   The default is classic for compatibility, since the themed widgets set a
+   themed background that classic widgets added in :meth:`body` would not match.
+
+   .. versionchanged:: next
+      Added the *use_ttk* parameter.
 
    .. attribute:: result
 
@@ -74,14 +84,32 @@ functions for creating simple modal dialogs to get a value from the user.
       the initial focus.
 
 
-.. class:: SimpleDialog(master, text='', buttons=[], default=None, cancel=None, title=None, class_=None)
+.. class:: SimpleDialog(master, text='', buttons=[], default=None, cancel=None, title=None, class_=None, *, bitmap=None, detail='', use_ttk=True)
 
    A simple modal dialog that displays the message *text* above a row of push
-   buttons whose labels are given by *buttons*, and returns the index of the
-   button the user presses.
-   *default* is the index of the button activated by the Return key, *cancel*
-   the index returned when the window is closed through the window manager,
-   *title* the window title, and *class_* the Tk class name of the window.
+   buttons given by *buttons*, and returns the index of the button the user
+   presses.
+   Each entry of *buttons* is either a button label, or a mapping of button
+   options such as ``{'text': 'OK', 'underline': 0}``; an ``underline`` option
+   makes :kbd:`Alt` plus the underlined character invoke the button.
+   *default* is the index of the default button, activated by the Return key
+   when no button has the focus, *cancel* the index returned when the window is
+   closed through the window manager, *title* the window title, and *class_*
+   the Tk class name of the window.
+   *bitmap* is the name of a bitmap displayed beside the message
+   (for example ``'warning'`` or ``'question'``); the standard names
+   ``'error'``, ``'info'``, ``'question'`` and ``'warning'`` are shown as
+   themed icons when *use_ttk* is true.
+   *detail* is a secondary message displayed below *text*.
+   When *use_ttk* is true (the default), the dialog is built from the themed
+   :mod:`tkinter.ttk` widgets, modelled on the Tk message box; when false, from
+   the classic :mod:`tkinter` widgets, modelled on ``tk_dialog``.
+
+   .. 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 *bitmap*, *detail* and *use_ttk* parameters.
+      Entries of *buttons* may be mappings of button options.
 
    .. method:: go()
 

Doc/whatsnew/3.16.rst

@@ -220,6 +220,22 @@ tkinter
   options as keyword arguments, which can also override its default appearance.
   (Contributed by Serhiy Storchaka in :gh:`101284`.)
 
+* The :mod:`tkinter.simpledialog` dialogs were modernized to match the look
+  and feel of the native Tk dialogs.
+  :class:`!tkinter.simpledialog.SimpleDialog` and the
+  :func:`~tkinter.simpledialog.askinteger`,
+  :func:`~tkinter.simpledialog.askfloat` and
+  :func:`~tkinter.simpledialog.askstring` dialogs are now built from the themed
+  :mod:`tkinter.ttk` widgets instead of the classic :mod:`tkinter` widgets;
+  the :class:`!tkinter.simpledialog.Dialog` base class still defaults to the
+  classic widgets for compatibility.  Both :class:`!Dialog` and
+  :class:`!SimpleDialog` gained a *use_ttk* parameter that selects between the
+  classic Tk widgets and the themed ttk widgets.  :class:`!SimpleDialog` also
+  gained *bitmap* and
+  *detail* parameters, draws the standard icons with themed images in the
+  ttk version, and accepts mappings of button options as *buttons* entries.
+  (Contributed by Serhiy Storchaka in :gh:`59396`.)
+
 xml
 ---