Can't delete files from open file dialog

This is a regression from qt 4

Steps to reproduce:
0) Create a temporary file, e.g. touch /tmp/xxxx
1) Open the standarddialog example: examples/widgets/dialogs/standarddialog
2) Open the getOpenFileNames dialog
3) navigate to /tmp, select the xxxx file and delete it
4) Nothing happens

This works with qt4. (Do note that you might need to uncheck the native dialogs checkbox).