HUD, Head-Up Display is Ubuntu’s new smart menus. But it may cause keyboard shortcut conflict if you playing Warcraft 3 what using “Alt” key to show HP. So sometimes you want to disable this feature or change its shortcut key.
To disable or re-enable this new feature in Ubuntu Unity, install compizconfig-settings-manager first:
sudo apt-get install compizconfig-settings-manager
Launch compizconfig-settings-manager, navigate to Ubuntu Unity Plugin -> Behaviour tab. There “Key to show the HUD” can adjust or disable the HUD key.