I am running Ubuntu 10.04 and I believe there is a bug in gnome-control-center 1:2.30.1-0ubuntu1. I have had a look at the Ubuntu BTS and I think I am experiencing the issue described here: https://bugs.launchpad.net/ubuntu/+source/gnome-control-center/+bug/515670/ I couldn't see any evidence of the original reporter forwarding the bug upstream so I am reporting it here. Apologies if this is fixed in a later version which I don't have an easy way to test.

Choose System->Preferences->Keyboard Shortcuts
The 'Keyboard Shortcuts' dialog appears
Click 'Add'
Enter name 'X' and command 'AnInvalidCommandToDemonstrate'
Click 'Apply'
The new shortcut appears under 'Custom Shortcuts' as 'Disabled'
Click on 'Disabled'
Press 'Alt Gr'
The new shortcut now appears with shortcut 'ISO Level3 Shift'
Press 'Alt Gr' (without clicking anywhere first)
An error appears when an attempt is made to execute the invalid command - fine
Highlight the shortcut and click 'Remove'
Press 'Alt Gr' (without clicking anywhere first)
An error appears when an attempt is made to execute the invalid command - this is not fine, I just removed that shortcut

I hope this makes sense. If you need any more information, please let me know.

Thanks.

Steve