[foobarqux]

If you use Emacs and depend on Ctrl-space note that you may have to disable the keybinding in ibus-setup and restart the ibus daemon. This bug was claimed to be fixed but it wasn't for me. However I'm running Xmonad with some Gnome utilities.

[_Satya]

The ibus in Ubuntu 14.04 uses Super+Space to switch between languages. Not the Ctrl+Space anymore. Nevertheless, it's easy to change it to any other key combination.

[foobarqux]

Mine was bound to Ctrl-space in ibus-setup but as I said I have a non-standard config.