I'm running in to a problem where TkInter won't update the display on OS X. I've attached a simple piece of code that has this problem, and I've also made a short screen-cast of the problem:

https://mywebspace.wisc.edu/lnmaurer/web/updatebug/updatebug.mov

The program is simple -- basically a big canvas with a some text in the middle that counts up.

The screen-cast has three parts. First, it shows the program working as it should. Then, I add a simple background image to the canvas (a black rectangle), and the interface refuses to refresh at all; I get a spinning beach ball wheel (although that doesn't show up in the screen-cast). Then, I increase the delay between updates, and the interface refreshes as it should.

The middle case, where the interface becomes totally unresponsive, is a bug.

I haven't been able to reproduce this problem under Linux or Windows; I've only run in to it on OS X. Also, the size of the canvas and image matters; if I make them small enough, the interface won't freeze up.

Computer and software information:
OS X 10.6.8
Python 2.7.3
ActiveTcl 8.5.13
PIL 1.1.7
MacBookPro5,5 w/ 2.26GHz Core 2 Duo (so a machine that's kind of slow by today's standards -- maybe faster machines won't run in to this problem, but this machine doesn't have the problem when running Windows or Linux)