What Jubber said.

This includes addons as well. When my priest is on my main window, I use the Healbot addon to help with raiding, but when she's on a slave window, I have no use for that addon. Ditto for Omen and Recount. In fact, most of my slaves use very few addons at all. I just don't want to have to remember to turn on/off addons every time I log in.