Created attachment 587549 [details]
screenshot shows missing icon for Thunderbird (and VLC)

Description of problem:
Gnome does not display the usual Thunderbird icon in association with the software.

Version-Release number of selected component (if applicable):
thunderbird-12.0.1-1.fc17.x86_64

How reproducible:
always

Steps to Reproduce:
1. Install Fedora 17 - the user home dir has not been erased and had been used with previous versions of Fedora.
2. Install Thunderbird
3. Look for Thunderbird.
 
Actual results:
The associated icon is teh "gear" default icon, not the usual Thunderbird icon.

Expected results:
The Thunderbird icon should be displayed instead.

Additional info:
The same problem occurs with VLC package vlc-2.0.1-1.fc17.x86_64 from rpmfusion.
Deleting ~/.local/share/applications as in bug #752558 doesn't help.