WIP: Display everything in a frame in the top window

By placing padding around this frame, we get around the problem of no
window borders on OS X.  Without this, mouse clicks/drags are
interpreted as a rubberband event as well as a resize event.  That 
confusion leads to fun resize behavior, where clicking on the window border
zooms in on a couple dozen pixels.

I'm guessing there is a better way to do this.

One side effect of this change is that it cuts down on the BoundsErrors (#1).
Doesn't eliminate them, however.