Sometimes there is case when two teams worked on the same piece of code, and changed it in similar way. In general their codes works in the same way, but there are some different pieces - e.g. code formatting, comments, logging, some extra if's, etc. Many times in such case during 3-way merge Kdiff is not very helpful, because it incorrectly determines which code from 2nd and 3rd contributor are equivalent. But when I compare 2nd and 3rd contributors only, it is much better with finding corresponding parts.
To do such diff now, I have to use temporary files and manually copy/paste code to them before diffing. Therefore I am asking for adding new functionality to Kdiff: allow to perform 2-way diff on selected parts of two contributors during 3-way merge. Diff result should be displayed in new non-modal window - I would like to move it to 2nd monitor, and be able to use both this window and original merge window at the same time.