In a Tkinter application that has an Entry() widget on the main window and an askopenfilename() dialog, one should be able to click and type into the Entry() widget as soon as the askopenfilename() dialog is closed. However, the askopenfilename() dialog renders the Entry() widget on the main window unusable/non-editable.

This issue was explored in http://mail.python.org/pipermail/tkinter-discuss/2010-August/002332.html at Tkinter-Discuss mailing list. All details relating to the issue can be followed from there.

It seems that only Windows OS is affected by this issue. In Ubuntu Karmic Koala (GNOME) and Debian (IceWM), at least, this issue cannot be reproduced, and everything works like expected.