Does someone have had this trouble on ubuntu - php storm doesn't see the declaration on classes somehow. On Windows system all works well.
My problem was that my whole vendor folder had somehow gotten ignored.
To check and fix, navigate to "File > Settings > Project Settings > Directories" and make sure that "vendor" is not excluded.
Sources: http://fuelphp.com/forums/discussion/3943/how-to-setup-code-completion-in-phpstorm