I have just tested again with your files, and I don't experience your issue.
From your screenshot, you seem to be using a theme, a skin or something, and not the default Ubuntu layout. Maybe this disturbs KDiff3 a bit more, or there is something else specific to your machine triggering the issue.
I have just tested again with your files, and I don't experience your issue.
From your screenshot, you seem to be using a theme, a skin or something, and not the default Ubuntu layout. Maybe this disturbs KDiff3 a bit more, or there is something else specific to your machine triggering the issue.