I can't use the shortcut for Organize Imports Ctrl+Alt+O action for Intellij IDEA on Ubuntu 14.04.
Note - I'm just posting it to help someone to avoid wasting time.
The problem was that I had
ClipIt 1.4.2 installed and Ctrl+Alt+O is set by default to the Off-line Mode hot-key.
As @mounir indicates in its comment,
gpaste gnome-extension also has the same shortcut.