Disable gnome-panel launcher (Alt+F2)

Solution 1:

You can disable Gnome Panel launcher using Gnome lockdown feature.

Execute this command:

gconftool-2 -t bool -s /desktop/gnome/lockdown/disable_command_line true

(You can inspect this option using gconf-editor) While Unity will ignore this setting, Gnome launcher will be effectively disabled.

Solution 2:

The better way is to reconfigure the shortcut for gnome-panel launcher. Run

gnome-keybinding-properties

and then, in the Desktop section, you'll see something like "Show the dialog box 'Launch an application' from panel" (sorry I don't know the translation in english) and change the keybord shortcut.