The problem can be reproduced on some other platforms depending on the version of Tcl/Tk in use.  But the supplied program violates the well-known if not particularly well-documented restriction of tkinter programming that all Tk UI operations must be on the main thread.  See, for example, http://effbot.org/zone/tkinter-threads.htm  or http://tkinter.unpythonic.net/wiki/mtTkinter