Thanks for the patch, Kevin. It does need to be updated a bit for the current 2.7 branch as there have been changes since 2.7.3.  Can you outline what you believe the problem is that your patch is trying to workaround?  Certainly, nothing that IDLE or any other tkinter-based application does should be able to cause a hard crash in Tk.  It seems very problematic to force a change to all existing versions of IDLE and require users to update their installed IDLEs just to work around a crash in the Cocoa Tk that was introduced by a specific recent checkin in Tk.  Since there have been other serious bugs in Cocoa Tk that have been corrected in every recent release of Cocoa Tk, it is pretty much incumbent on users to keep up with the latest available version.