Tix.PanedWindow.panes() is nonfunctional for any but single-letter pane names; the culprit is the following line of code from Tix.PanedWindow.panes: names = self.tk.call(self._w, 'panes') Since the Tk "panes" command returns a string, it is not iterated over properly. The fix is: names = self.tk.split(self.tk.call(self._w, 'panes')) Attached is error log from Python 2.4, Windows 2k.
Is there some reason to prefer .split over .splitlist ? It is very likely that .split would still return a string if you had a single pane, while .splitlist would return a tuple with an item on it. Patch attached.