Beta 3 improved the behavior, but still has an unnecessary scrolling of the fragment editor, however, the controls stay half visible, while having been gone in beta 2. attached Screenshots taken in beta 2.
Original Forum text pasted:
Fragment opened, the page with the 3 editors and 1 preview spans the visible area right of the Control Panel. However, it's larger than necessary, causing the browser (Firefox/Linux in my case) to scroll. Once I touch the scrollbar, I'm hiding the "Save Draft" and "Publish" buttons on top of the editors.
See the two screenshots - first before scrolling, second after scrolling (it might be hard to spot the difference - search for the "Publish" button on both, only one contains it)