Zoom in on frames in bottom horizontal panel

First time user, here. I have a short (short!) animation, with a total of 4 seconds, or 48 frames.

Is there any way I can change the display of the bottom panel so that it will be filled with the frames and not have any unused space on the right? (I’ve already discovered how easy it is to drag frames out of order)

(and what is that horizontal strip at the bottom called? I would have preferred to refer to it by the right name (and search the forum using that name)