I've used kdiff3 a lot on windows. It's not bad, shows a readable 3-way-diff format (which I need to stretch over two screens to read the full lines). Reasonabl

I've used kdiff3 a lot on windows. It's not bad, shows a readable 3-way-diff format (which I need to stretch over two screens to read the full lines). Reasonably fast startup too. But it lacks any sort of advanced editing functionality, such as undo.