Center "fit to screen" between open side panels

Currently the "fit to screen" button will center the scene between the browser borders. This looks odd, when having the Sidepanels expanded, because they are not of equal size. It's even more bothering, when having only one of the sidepanels open, the there is just an odd amount of whitespace to the side of the canvas.

Minor inconvenience, but maybe you could change this :)