How to use SelectionListener with CheckinProjectPanel in #922

since the 6xx Builds we were using a selection listener on the CheckinProjectPanel to provide per-file-checking-message in our VCS integration. This is now broken in #922: selectionChanged() on the registered listener gets called, but ctxt.getData(DataConstants.VIRTUAL_FILE_ARRAY) now alwas returns null.

Is there any way to determine which entries are currently selected in the CheckinProjectPanel's TreeView?