I assumed it was a shared alternating button, so yeah I was wrong, but it's surprising to me you are that hurt for bars. Is it PVP skills or something? As is I have enough spots for everything on WAR even on controller. I think the only thing I'm hurt for on it is SCH for all the pet nonsense.
Speaking of, how do you fit all of your DRK abilities on crossbars for controller? I've been messing with different ways to do it but I hate everything I've done so far.