selection model better handled.
now we get the bug that I reported to TT some time ago: if you use the rubberband with ctrl clicked you lose the _last selection_ done. example: ctrl+click foo.txt, ctrl+click bar.txt, now rubberband with ctrl pressed: bar.txt becomes unselected.

I think this is a QItemSelectionModel bug, but we need to go deeper in the correct use of this class since that bug seemed to have been fixed on QListView with the latest Qt release