Selecting Widgets Causes Widget List to Creep Right

[LionKimbro]

Clicking on a widget in the list of instantiated widgets (underneath "Widget Id, Class, R, C") causes the Widget List (with tk and ttk controls) to creep in size to the right.

Platform: Windows 7, Python 3.3

Reproduction steps:

1. expand tk under Widget List
2. expand Containers
3. double click Frame
4. Click on "Frame_#" underneath Widget Id, to select it.
5. Keep clicking on it, just like in step 4. (In repetition)

Observed: Widget List pane gets wider and wider by one pixel with each click.
Expected: Widget List pane keeps the same width.