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Installed Ubuntu 12.04 64bit today, switched to Gnome Classic (no effects) and there is one thing that makes me crazy: I can't assign Super+L to Lock Screen function!

I go to System Settings -> Keyboard -> Shortcuts -> System, then I click on Lock Screen and press "Super + L", it appears in the list but when I press it again it doesn't work.

If I set it back to Ctrl+Alt+L it works again. Actually, I tried to set it to different Super + ?? combinations, and neither of them work.

if I assign Super+L to so other command, like Start Terminal, it works.

marked as duplicate by Warren Hill, belacqua, LiveWireBT, karel, Jorge Castro Oct 24 '13 at 1:22

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Found a solution:

run gconf-editor

Set values:

/apps/metacity/global_keybindings/run_command_1  <Super>L
/apps/metacity/keybinding_commands/command_1 gnome-screensaver-command -l

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