gh-113951: Tkinter: "tag_unbind(tag, sequence, funcid)" now only unbinds "funcid" (GH-113955)

Previously, "tag_unbind(tag, sequence, funcid)" methods of Text and
Canvas widgets destroyed the current binding for "sequence", leaving
"sequence" unbound, and deleted the "funcid" command.

Now they remove only "funcid" from the binding for "sequence", keeping
other commands, and delete the "funcid" command.
They leave "sequence" unbound only if "funcid" was the last bound command.

Lib/test/test_tkinter/test_misc.py

@@ -706,6 +706,101 @@ class BindTest(AbstractTkTest, unittest.TestCase):
         self.assertCommandExist(funcid2)
         self.assertCommandExist(funcid3)
 
+    def _test_tag_bind(self, w):
+        tag = 'sel'
+        event = '<Control-Alt-Key-a>'
+        w.pack()
+        self.assertRaises(TypeError, w.tag_bind)
+        tag_bind = w._tag_bind if isinstance(w, tkinter.Text) else w.tag_bind
+        if isinstance(w, tkinter.Text):
+            self.assertRaises(TypeError, w.tag_bind, tag)
+            self.assertRaises(TypeError, w.tag_bind, tag, event)
+        self.assertEqual(tag_bind(tag), ())
+        self.assertEqual(tag_bind(tag, event), '')
+        def test1(e): pass
+        def test2(e): pass
+
+        funcid = w.tag_bind(tag, event, test1)
+        self.assertEqual(tag_bind(tag), (event,))
+        script = tag_bind(tag, event)
+        self.assertIn(funcid, script)
+        self.assertCommandExist(funcid)
+
+        funcid2 = w.tag_bind(tag, event, test2, add=True)
+        script = tag_bind(tag, event)
+        self.assertIn(funcid, script)
+        self.assertIn(funcid2, script)
+        self.assertCommandExist(funcid)
+        self.assertCommandExist(funcid2)
+
+    def _test_tag_unbind(self, w):
+        tag = 'sel'
+        event = '<Control-Alt-Key-b>'
+        w.pack()
+        tag_bind = w._tag_bind if isinstance(w, tkinter.Text) else w.tag_bind
+        self.assertEqual(tag_bind(tag), ())
+        self.assertEqual(tag_bind(tag, event), '')
+        def test1(e): pass
+        def test2(e): pass
+
+        funcid = w.tag_bind(tag, event, test1)
+        funcid2 = w.tag_bind(tag, event, test2, add=True)
+
+        self.assertRaises(TypeError, w.tag_unbind, tag)
+        w.tag_unbind(tag, event)
+        self.assertEqual(tag_bind(tag, event), '')
+        self.assertEqual(tag_bind(tag), ())
+
+    def _test_tag_bind_rebind(self, w):
+        tag = 'sel'
+        event = '<Control-Alt-Key-d>'
+        w.pack()
+        tag_bind = w._tag_bind if isinstance(w, tkinter.Text) else w.tag_bind
+        self.assertEqual(tag_bind(tag), ())
+        self.assertEqual(tag_bind(tag, event), '')
+        def test1(e): pass
+        def test2(e): pass
+        def test3(e): pass
+
+        funcid = w.tag_bind(tag, event, test1)
+        funcid2 = w.tag_bind(tag, event, test2, add=True)
+        script = tag_bind(tag, event)
+        self.assertIn(funcid2, script)
+        self.assertIn(funcid, script)
+        self.assertCommandExist(funcid)
+        self.assertCommandExist(funcid2)
+
+        funcid3 = w.tag_bind(tag, event, test3)
+        script = tag_bind(tag, event)
+        self.assertNotIn(funcid, script)
+        self.assertNotIn(funcid2, script)
+        self.assertIn(funcid3, script)
+        self.assertCommandExist(funcid3)
+
+    def test_canvas_tag_bind(self):
+        c = tkinter.Canvas(self.frame)
+        self._test_tag_bind(c)
+
+    def test_canvas_tag_unbind(self):
+        c = tkinter.Canvas(self.frame)
+        self._test_tag_unbind(c)
+
+    def test_canvas_tag_bind_rebind(self):
+        c = tkinter.Canvas(self.frame)
+        self._test_tag_bind_rebind(c)
+
+    def test_text_tag_bind(self):
+        t = tkinter.Text(self.frame)
+        self._test_tag_bind(t)
+
+    def test_text_tag_unbind(self):
+        t = tkinter.Text(self.frame)
+        self._test_tag_unbind(t)
+
+    def test_text_tag_bind_rebind(self):
+        t = tkinter.Text(self.frame)
+        self._test_tag_bind_rebind(t)
+
     def test_bindtags(self):
         f = self.frame
         self.assertEqual(self.root.bindtags(), ('.', 'Tk', 'all'))