gh-154357: Take the focus right before generating a key event

update() between focus_force() and event_generate() gives the window
manager a chance to take the focus away.  Tk then drops the generated
key event, because it delivers it to the window which has the focus.

Author: serhiy-storchaka

Lib/idlelib/idle_test/test_configdialog.py

@@ -150,8 +150,8 @@ def test_fontlist_key(self):
         font = d.fontlist.get('active')
 
         # Test Down key.
-        fontlist.focus_force()
         fontlist.update()
+        fontlist.focus_force()
         fontlist.event_generate('<Key-Down>')
         fontlist.event_generate('<KeyRelease-Down>')
 
@@ -160,8 +160,8 @@ def test_fontlist_key(self):
         self.assertIn(d.font_name.get(), down_font.lower())
 
         # Test Up key.
-        fontlist.focus_force()
         fontlist.update()
+        fontlist.focus_force()
         fontlist.event_generate('<Key-Up>')
         fontlist.event_generate('<KeyRelease-Up>')
 

Lib/test/test_tkinter/test_filedialog.py

@@ -164,8 +164,8 @@ def test_alt_key(self):
         d = self.open()
         invoked = []
         d.cancel_button.configure(command=lambda: invoked.append(True))
-        d.top.focus_force()
         d.top.update()
+        d.top.focus_force()
         d.top.event_generate('<Alt-c>')  # "&Cancel"
         d.top.update()
         self.assertTrue(invoked)
@@ -174,8 +174,8 @@ 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.focus_force()
         d.top.event_generate('<Escape>')
         d.top.update()
         self.assertIsNone(d.how)

Lib/test/test_tkinter/test_simpledialog.py

@@ -45,8 +45,8 @@ def test_use_ttk(self):
                          ttk.Style(d.root).lookup('.', 'background'))
         # The bindings work with the themed buttons too.
         self.require_mapped(d.root)
-        d._buttons[0].focus_force()
         d.root.update()
+        d._buttons[0].focus_force()
         d.root.event_generate('<Return>')
         d.root.update()
         self.assertEqual(d.num, 0)
@@ -144,8 +144,8 @@ def test_alt_key(self):
         # the matching button (cf. tk::AmpWidget in tk::MessageBox).
         d = self.create(buttons=['Yes', {'text': 'No', 'underline': 0}])
         self.require_mapped(d.root)
-        d._buttons[0].focus_force()
         d.root.update()
+        d._buttons[0].focus_force()
         d.root.event_generate('<Alt-n>')  # "No" -> underline 0 -> "N"
         d.root.update()
         self.assertEqual(d.num, 1)
@@ -155,8 +155,8 @@ def test_return_invokes_focused_button(self):
         # default and the focus was not moved by keyboard traversal.
         d = self.create(buttons=['Yes', 'No'])  # default 0
         self.require_mapped(d.root)
-        d._buttons[1].focus_force()
         d.root.update()
+        d._buttons[1].focus_force()
         d.root.event_generate('<Return>')
         d.root.update()
         self.assertEqual(d.num, 1)
@@ -165,8 +165,8 @@ def test_focus_next_then_return(self):
         # <Tab> moves the focus to the next button; <Return> invokes it.
         d = self.create(buttons=['Yes', 'No'])
         self.require_mapped(d.root)
-        d._buttons[0].focus_force()
         d.root.update()
+        d._buttons[0].focus_force()
         d._buttons[0].event_generate('<Tab>')
         d.root.update()
         d.root.event_generate('<Return>')
@@ -177,8 +177,8 @@ def test_focus_prev_then_return(self):
         # <Shift-Tab> moves the focus to the previous button.
         d = self.create(buttons=['Yes', 'No'])
         self.require_mapped(d.root)
-        d._buttons[1].focus_force()
         d.root.update()
+        d._buttons[1].focus_force()
         d._buttons[1].event_generate('<Shift-Tab>')
         d.root.update()
         d.root.event_generate('<Return>')
@@ -189,8 +189,8 @@ def test_return_activates_default(self):
         # <Return> with the focus off the buttons invokes the default button.
         d = self.create()  # default 0
         self.require_mapped(d.root)
-        d.root.focus_force()  # the dialog, not a button, has the focus
         d.root.update()
+        d.root.focus_force()  # the dialog, not a button, has the focus
         d.root.event_generate('<Return>')
         d.root.update()
         self.assertEqual(d.num, 0)
@@ -279,8 +279,8 @@ def test_use_classic(self):
         invoked = []
         cancel = d.children['cancel']
         cancel.configure(command=lambda: invoked.append(True))
-        cancel.focus_force()
         d.update()
+        cancel.focus_force()
         d.event_generate('<Return>')
         d.update()
         self.assertTrue(invoked)
@@ -359,8 +359,8 @@ def test_alt_key(self):
         invoked = []
         cancel = d.children['cancel']  # "&Cancel"
         cancel.configure(command=lambda: invoked.append(True))
-        d.focus_force()
         d.update()
+        d.focus_force()
         d.event_generate('<Alt-c>')
         d.update()
         self.assertTrue(invoked)
@@ -371,8 +371,8 @@ def test_return_invokes_focused_button(self):
         invoked = []
         cancel = d.children['cancel']
         cancel.configure(command=lambda: invoked.append(True))
-        cancel.focus_force()
         d.update()
+        cancel.focus_force()
         d.event_generate('<Return>')
         d.update()
         self.assertEqual(invoked, [True])
@@ -384,8 +384,8 @@ def test_focus_next_then_return(self):
         for name in ('ok', 'cancel'):
             d.children[name].configure(command=lambda name=name: invoked.append(name))
         ok = d.children['ok']
-        ok.focus_force()
         d.update()
+        ok.focus_force()
         ok.event_generate('<Tab>')  # OK -> Cancel
         d.update()
         d.event_generate('<Return>')
@@ -399,8 +399,8 @@ def test_focus_prev_then_return(self):
         for name in ('ok', 'cancel'):
             d.children[name].configure(command=lambda name=name: invoked.append(name))
         cancel = d.children['cancel']
-        cancel.focus_force()
         d.update()
+        cancel.focus_force()
         cancel.event_generate('<Shift-Tab>')  # Cancel -> OK
         d.update()
         d.event_generate('<Return>')