Open File window gives no feedback when bad files are imported

1) Ubuntu 11.04
2) PPA
3) 1.3.1

Steps to reproduce:
1) Start OpenShot
2) Press Ctrl+F or similar to see the Import Files form
3) Import a file that should not be able to be imported, like an .exe file, or an empty folder, or some files you already have imported.
4) Click "Add". You get no feedback.

What should happen:
It should show a messagebox when:
You open a file type not supported
You open an empty folder
You open a file that already has been imported
A combination of those above

If at least one file is ok, no messagebox should be shown, since you could actually import a folder with almost only "good" files and don't want some irritating messageboxes.

Patch below.