Instead of "back" can we call this "Top" or something?  It takes you to the main documentation page, which we call "top" on the left nav bar, and it's not really "back" because if you came in through Sandcastle (the only way to see this link) you likely haven't been there yet.

Also I'd be tempted to switch the left and right arrows here with more typical "home" and wikipedia-style pop-out icons.