With this, the KateSaveModifiedDialog distinguishes if only one file has been changed, or multiple ones. If the former is the case, it looks similar to a QMessageBox::warning dialog only asking to save or discard that very file (or to cancel of course).
If multiple files have been changed, the dialog looks like before.
This way, we get a more straightforward UI, as the QTreeWidget shown by default is pointless if we only talk about one file. Also, we get the behavior of good ole KWrite back a bit more ;-)