[acqq]

Can they be even compared? KDiff3 merges based on the "common ancestor" (3 versions to the fourth) and I don't see in that feature in the screenshots of WinMerge?

[schumihan]

Most of the time, I use both as a tool to do visual diff, instead of code merge.

KDiff3 is not so good as winmerge as visual diff tool. And kdiff3 UI has small problem on Ubuntu, as it was not developed for gnome environment.