gh-75234: Fix keyboard selection in the lists of IDLE Settings (#157588)

The Up and Down keys move the selection in the help sources and key
bindings lists, but not the anchor. So the buttons that act on the
selected item stayed disabled, and acted on the anchored item instead
of the selected one. Move the anchor on the key events, as the font
list already does.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* Select the first key binding when the list is loaded

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: serhiy-storchaka

Lib/idlelib/configdialog.py

@@ -1146,8 +1146,8 @@ def create_page_keys(self):
         selected keyset.  The keybindings are loaded in load_keys_list()
         and are pairs of (event, [keys]) where keys can be a list
         of one or more key combinations to bind to the same event.
-        Mouse button 1 click invokes on_bindingslist_select(), which
-        allows button_new_keys to be clicked.
+        Mouse button 1 click or Up or Down key invokes
+        on_bindingslist_select(), which allows button_new_keys to be clicked.
 
         So, an item is selected in listbindings, which activates
         button_new_keys, and clicking button_new_keys calls function
@@ -1221,9 +1221,12 @@ def create_page_keys(self):
         scroll_target_y = Scrollbar(frame_target)
         scroll_target_x = Scrollbar(frame_target, orient=HORIZONTAL)
         self.bindingslist = Listbox(
-                frame_target, takefocus=FALSE, exportselection=FALSE)
+                frame_target, takefocus=True, exportselection=FALSE)
         self.bindingslist.bind('<ButtonRelease-1>',
                                self.on_bindingslist_select)
+        self.bindingslist.bind('<KeyRelease-Up>', self.on_bindingslist_select)
+        self.bindingslist.bind('<KeyRelease-Down>',
+                               self.on_bindingslist_select)
         scroll_target_y['command'] = self.bindingslist.yview
         scroll_target_x['command'] = self.bindingslist.xview
         self.bindingslist['yscrollcommand'] = scroll_target_y.set
@@ -1427,7 +1430,14 @@ def save_as_new_key_set(self):
             self.create_new_key_set(new_keys_name)
 
     def on_bindingslist_select(self, event):
-        "Activate button to assign new keys to selected action."
+        """Activate button to assign new keys to selected action.
+
+        Event can result from either mouse click or Up or Down key.
+        The keys move the selection, but not the anchor used by
+        get_new_keys and var_changed_keybinding.
+        """
+        if event.type.name == 'KeyRelease':
+            self.bindingslist.selection_anchor(ACTIVE)
         self.button_new_keys.state(('!disabled',))
 
     def create_new_key_set(self, new_key_set_name):
@@ -1465,9 +1475,8 @@ def load_keys_list(self, keyset_name):
 
         An action/key binding can be selected to change the key binding.
         """
-        reselect = False
+        list_index = 0
         if self.bindingslist.curselection():
-            reselect = True
             list_index = self.bindingslist.index(ANCHOR)
         keyset = idleConf.GetKeySet(keyset_name)
         # 'set' is dict mapping virtual event to list of key events.
@@ -1482,10 +1491,11 @@ def load_keys_list(self, keyset_name):
                 if bind_name in changes['keys'][keyset_name]:
                     key = changes['keys'][keyset_name][bind_name]
             self.bindingslist.insert(END, bind_name+' - '+key)
-        if reselect:
-            self.bindingslist.see(list_index)
-            self.bindingslist.select_set(list_index)
-            self.bindingslist.select_anchor(list_index)
+        self.bindingslist.see(list_index)
+        self.bindingslist.select_set(list_index)
+        self.bindingslist.select_anchor(list_index)
+        self.bindingslist.activate(list_index)
+        self.button_new_keys.state(('!disabled',))
 
     @staticmethod
     def save_new_key_set(keyset_name, keyset):
@@ -2124,6 +2134,8 @@ def create_frame_help(self):
         scroll_helplist['command'] = self.helplist.yview
         self.helplist['yscrollcommand'] = scroll_helplist.set
         self.helplist.bind('<ButtonRelease-1>', self.help_source_selected)
+        self.helplist.bind('<KeyRelease-Up>', self.help_source_selected)
+        self.helplist.bind('<KeyRelease-Down>', self.help_source_selected)
 
         frame_buttons = Frame(self)
         self.button_helplist_edit = Button(
@@ -2146,7 +2158,14 @@ def create_frame_help(self):
         self.button_helplist_remove.pack(side=TOP, anchor=W, pady=5)
 
     def help_source_selected(self, event):
-        "Handle event for selecting additional help."
+        """Handle event for selecting additional help.
+
+        Event can result from either mouse click or Up or Down key.
+        The keys move the selection, but not the anchor used by
+        helplist_item_edit and helplist_item_remove.
+        """
+        if event.type.name == 'KeyRelease':
+            self.helplist.selection_anchor(ACTIVE)
         self.set_add_delete_state()
 
     def set_add_delete_state(self):

Lib/idlelib/idle_test/test_configdialog.py

@@ -9,7 +9,9 @@
 import unittest
 from unittest import mock
 from idlelib.idle_test.mock_idle import Func
-from tkinter import (Tk, StringVar, IntVar, BooleanVar, DISABLED, NORMAL)
+from tkinter import (Tk, StringVar, IntVar, BooleanVar, DISABLED, NORMAL,
+                     EventType)
+from types import SimpleNamespace
 from idlelib import config
 from idlelib.configdialog import idleConf, changes, tracers
 
@@ -1060,6 +1062,14 @@ def test_on_bindingslist_select(self):
         self.assertEqual(b.get('anchor'), 'find')
         self.assertNotIn('disabled', d.button_new_keys.state())
 
+        # gh-75234: Up and Down keys move the active item, but not the
+        # anchor; the handler moves the anchor.
+        d.button_new_keys.state(('disabled',))
+        b.activate(0)
+        d.on_bindingslist_select(SimpleNamespace(type=EventType.KeyRelease))
+        self.assertEqual(b.get('anchor'), 'copy')
+        self.assertNotIn('disabled', d.button_new_keys.state())
+
     def test_create_new_key_set_and_save_new_key_set(self):
         eq = self.assertEqual
         d = self.page
@@ -1110,11 +1120,14 @@ def test_load_keys_list(self):
                     'force-open-completions - <Control-Key-space>',
                     'spam - <Shift-Key-a>')
 
-        # No current selection.
+        # No current selection: select the first item.
+        d.button_new_keys.state(('disabled',))
         d.load_keys_list('my keys')
         eq(b.get(0, 'end'), expected)
-        eq(b.get('anchor'), '')
-        eq(b.curselection(), ())
+        eq(b.get('anchor'), 'copy - <Control-Key-c> <Control-Key-C>')
+        eq(b.curselection(), (0, ))
+        eq(b.index('active'), 0)
+        self.assertNotIn('disabled', d.button_new_keys.state())
 
         # Check selection.
         b.selection_set(1)
@@ -1584,6 +1597,26 @@ def test_helplist_item_remove(self):
         eq(fr.user_helplist, [])
         self.assertTrue(fr.upc.called == fr.set.called == 1)
 
+    def test_helplist_item_remove_keyboard_selection(self):
+        # gh-75234: Up and Down keys move the active item, but not the
+        # anchor; the handler moves the anchor.
+        eq = self.assertEqual
+        fr = self.frame
+        fr.helplist.delete(0, 'end')
+        fr.helplist.insert('end', 'name1', 'name2')
+        fr.helplist.selection_anchor(0)
+        fr.helplist.selection_set(1)
+        fr.helplist.activate(1)
+        fr.user_helplist.clear()
+        fr.user_helplist.extend([('name1', 'file1'), ('name2', 'file2')])
+        fr.set.called = fr.upc.called = 0
+
+        fr.help_source_selected(SimpleNamespace(type=EventType.KeyRelease))
+        eq(fr.helplist.get('anchor'), 'name2')
+        fr.helplist_item_remove()
+        eq(fr.helplist.get(0, 'end'), ('name1',))
+        eq(fr.user_helplist, [('name1', 'file1')])
+
     def test_update_help_changes(self):
         fr = self.frame
         self.addCleanup(setattr, fr, 'update_help_changes', Func())  # Re-mask method.

Misc/NEWS.d/next/IDLE/2026-09-15-20-14-08.gh-issue-75234.O8ZNFV.rst

@@ -0,0 +1,2 @@
+Fix editing help sources and key bindings in the IDLE Settings dialog after
+selecting them with the keyboard.