I concur with the Dude. The main reason I never used Playing Now in the Action Window is that it kept disappearing on me, just when I wanted to drag more tracks into it. Display window and playing now, STICKY, in the lower left corner.
BTW, currently the display window disappears if you open Playing now in a view. This is just wrong. MC needs to tack down one or two things, IMO, and PN and the display window in the lower left corner is a great place to start.