The unbind docstring, "Unbind for this widget for event SEQUENCE the
function identified with FUNCID" implies to me the behavior Juliette expected.  The NMT reference unpacks this to two sentences.  Reading the code
        self.tk.call('bind', self._w, sequence, '')
        if funcid:
            self.deletecommand(funcid)

the docstring should be something like "Unbind for this widget the event SEQUENCE.  If funcid is given, delete the command also"  This part of the bind docstring, "Bind will return an identifier to allow deletion of the bound function with unbind without memory leak." implies that the unbind behavior is deliberate.

Serhiy, are you proposing to add a new method that does what some people thought unbind would do?