One final data point: I was unable to reproduce the failure when using a Python 3.2.3 when linked with a current ActiveState Tcl/Tk 8.4, which uses an older Aqua Carbon Tk.  The python.org 32-bit-only Pythons use Tcl/Tk 8.4 like this; see http://www.python.org/download/mac/tcltk/ for more info.  No guarantee that the problem won't show up there for you or that there won't be other issues (for instance, the Aqua Carbon Tcl/Tk is only available in 32-bit mode) but it *might* be worth a try.  Given Kevin's response to your enquiry on the Mac Tcl list, the consensus seems to be that the problem here is indeed in the Cocoa port of Tcl/Tk and is unlikely to be addressed there soon.  Sorry!

http://permalink.gmane.org/gmane.comp.lang.tcl.mac/7029