I never do, but you can. It just pulls the interface back a few more pixels, but if you want full screen every little bit helps. Another tip when I am rendering larger images is to leave my document resolution at 960x720 and turn up the "render resolution" way up. I click on the render button to start the render, then stop it after a few lines. Next I click the little "minus" sign (lower right corner) until the render is small enough to see the whole frame. Then I start the render over again. This allows me to see the entire image as it renders for the next day or so. ;-)