Comment 1 for bug 772224

In the latter case (diff tool not supporting tabs), the clean-up could occur when the pop-up window has been closed and ALL subprocesses created by the pop-up window had finished. This way, you could double-click to open one file diff and then switch back to the pop-up and double-click to open a second one.

As well as allowing multiple file diffs at the same time, this would also mean that if qbzr doesn't realise that a diff tool supports tabbing (e.g. if a new version comes out), each file that is double-clicked would probably end up in a new tab anyway. Not as clean as just opening them all in tabs straight-away, but better than having to keep creating new windows every time.