The result: Before I managed to cancel, a few hundred files that were deleted/moved/renamed in the working directory got filled in by files from the backup. There's no way for me to find those files, as the file dates are scattered (as they should) and after canceling, the list is cleared while it re-scans.
Two (and a half) ways to prevent this the next time (the feature request):
- -undo function
-don't clear the list so I can select the files on the right (blue, singles) and mark them for deletion on the left(!) side
-don't clear the list so I can scroll around and inspect which files were copied (the manual way; with pen and paper if needed)