Disable Logout Menu when Panel is Locked

When locking the panel the Logout Help and About menus are still available. With a locked down version of Linux for users working from home on a bootable USB we do not want the user to have the ability to Logout. Shutdown, Suspend Switch User can be disabled but not Logout.

Proposed solution: In function panel_window_menu_popup the statement if (!panel_window_get_locked (window)) { could be extended to wrap around the /* logout item */ from line 3646 and disable Logout menu as well when locked.

Thank you for your consideration.