Please describe the problem:
When the option "Show position of pointer when the Control key is pressed" is enabled, some global shortcuts registered by other applications break. 

Any global shortcut key combination which uses the Control key as it's only modifier key is affected. 

These key combinations don't operate unless the registering application has focus, or the combination is entered twice in rapid succession.

Re-registering key combinations doesn't help. 

This may be a bug in Metacity. 

I've filled this bug as 'Major' severity, since it interferes with unrelated aspects of the Desktop. 

Steps to reproduce:
1. Use the GNOME Keyboard Shortcuts panel to register the combination Control+F12 to some task (e.g., maximize a window). 
2. Verify that the function works as expected
2. Open the Mouse Preferences panel of GNOME Control Center
3. Enable the option labelled "Show position of pointer when the Control key is pressed"
4. Observe that the Control+F12 combination no longer works. 
5. Disable the "Show position..." option 
6. Observe that the Control+F12 shortcut works again. 


Actual results:
Global key combinations of form Control+<...> don't have any effect.

Expected results:
Global key combinations should operate at any time, unless an application with focus overwrites them. 

Does this happen every time?
Yes, unless the combination is pressed twice in rapid succession, or the application which registered the combination has focus.

Other information:
Running Ubuntu Intrepid with the following packages installed:

gnome-control-center 1:2.24.0.1-0ubuntu1
metacity 1:2.24.0-0ubuntu1