I second that the title should start with the filename, by default.  This seems to be the precedent, and it makes it easy when working with multiple files.

Example:
xxx.py - IDLE x.y.z: C:\mydir\xxx.py

Terry, I think we can generalize this as '<important/useful title> - <general>: <specific>' and apply it to all windows.  The first element essentially guarantees that the title name will be a good one for the taskbar.  We can apply this to say the FIF output window:
Matches for "hello" - IDLE x.y.z: C:\output.txt

but maybe everything after the hyphen isn't necessary.  I wonder if long titles could be annoying or distracting.  Regardless, anything more specific than 'Output Window' will be better.