When diffing filenames that is too long, tkdiff will increase the size of the window to fit the filename in order to not hide text. This overrides the window size defined in .tkdiffrc. Also, when manually resize the window in such a case, tkdiff will claim to be still at 80x60 or whatever you set it to be even though when it is bigger than that
Affected version:
I tried it on 3.09 and the newest 4.1.4
to be more obvious, try this:
1) set tkdiff to default to 80 characters wide;
2) tkdiff something with a long filename, e.g. 100 characters total;
3) resize the window width until it shows 1x*, which suggests that the window is 1 character wide while it is obviously not
email is ivan (at) hkgeex (dot) com if interested in following up
As of V4.3 (maybe earlier) this doesn't appear to be the case. Then again, as an anonymous ticket, why I'm responding is beyond me. Still, thanks for your concern and the time to report it.