#105 Null key in Tree(HList) causes odd exception

[Raymond Guilbault]

I am using Tix 8.4.3 from Python 3.2.1. Both installed from Fedore 16 packages. I am loading a file into a Tree(HList) widget which has a null key field. The code is in the FileSelectDialog command callback. The null key causes a weird exception when autosetmode is called.
Exception in Tkinter callback
Traceback (most recent call last):
File "/usr/lib64/python3.2/tkinter/__init__.py", line 1399, in __call__
return self.func(*args)
File "csvviewer.py", line 114, in openfile
self.treeview.autosetmode()
File "/usr/lib64/python3.2/tkinter/tix.py", line 1539, in autosetmode
self.tk.call(self._w, 'autosetmode')
_tkinter.TclError: too many nested evaluations (infinite loop?)

The autosetmode is done in a callback. The remainder of the callback does not execute but the program keeps running. The add method does not raise an exception on a null key even though it will cause problems with other parts of the widget.