pythongh-75666: Tkinter: "unbind(sequence, funcid)" now only unbinds "funcid"

Previously, "widget.unbind(sequence, funcid)" destroyed the current binding
for "sequence", leaving "sequence" unbound, and deleted the "funcid"
command.

Now it removes only "funcid" from the binding for "sequence", keeping
other commands, and deletes the "funcid" command.
It leaves "sequence" unbound only if "funcid" was the last bound command.

Co-authored-by: GiovanniL <[email protected]>

Author: serhiy-storchaka

Lib/test/test_tkinter/test_misc.py

@@ -491,6 +491,8 @@ def test2(e): pass
         f.unbind(event, funcid)
         script = f.bind(event)
         self.assertNotIn(funcid, script)
+        self.assertIn(funcid2, script)
+        self.assertEqual(f.bind(), (event,))
         self.assertCommandNotExist(funcid)
         self.assertCommandExist(funcid2)
 

Lib/tkinter/__init__.py

@@ -1527,10 +1527,21 @@ def bind(self, sequence=None, func=None, add=None):
         return self._bind(('bind', self._w), sequence, func, add)
 
     def unbind(self, sequence, funcid=None):
-        """Unbind for this widget for event SEQUENCE  the
-        function identified with FUNCID."""
-        self.tk.call('bind', self._w, sequence, '')
-        if funcid:
+        """Unbind for this widget the event SEQUENCE.
+
+        If FUNCID is given, only unbind the function identified with FUNCID
+        and also delete that command.
+        """
+        if funcid is None:
+            self.tk.call('bind', self._w, sequence, '')
+        else:
+            lines = self.tk.call('bind', self._w, sequence).split('\n')
+            prefix = f'if {{"[{funcid} '
+            keep = '\n'.join(line for line in lines
+                             if not line.startswith(prefix))
+            if not keep.strip():
+                keep = ''
+            self.tk.call('bind', self._w, sequence, keep)
             self.deletecommand(funcid)
 
     def bind_all(self, sequence=None, func=None, add=None):

Misc/NEWS.d/next/Library/2023-10-25-16-37-13.gh-issue-75666.BpsWut.rst

@@ -0,0 +1,6 @@
+Change the behavior of :mod:`tkinter` widget's ``unbind()`` method with two
+arguments. Previously, ``widget.unbind(sequence, funcid)`` destroyed the
+current binding for *sequence*, leaving *sequence* unbound, and deleted the
+*funcid* command. Now it removes only *funcid* from the binding for
+*sequence*, keeping other commands, and deletes the *funcid* command. It
+leaves *sequence* unbound only if *funcid* was the last bound command.