I first saw this when upgrading from the last shipped OSX binary to macports kdiff3 (probably 0.9.96). I reproduced it by building kdiff3, apparently against macports qt4-mac @4.8.2. I am attaching two pairs of screenshot of a diff run on the README between 0.9.96 and 0.9.97. Each pair has a regular display and one with some selected text.
- kdiff3-diff1 exhibits display problems, mostly overlapping characters on regular text. The effect disappears on selected text.
- kdiff3-diff2 exhibits the same kind of artifacts but selecting turns overlapping characters into clipped characters.
There is a similar effect in the merge panel which makes editing almost unusable: there is clearly a problem with font size calculation, clicking on one character would move the caret before another, plus the previous display problems.
I might find time on my side to investigate this but I know nothing of QT, if you want me to test things do not hesitate, and if you have pointers to enter the code...