Unclear what "Diff All Modified Files" is supposed to mean

1. Start Creator without opening any files or projects.
2. Go to "Tools" -> "Diff" -> "Diff All Modified Files"
   The diffeditor will appear, showing "No differences".

No differences where? If this is showing the differences in open files or open projects, it should be disabled when nothing was opened. If it gets data from somewhere else, it should make that more clear.