Especially the right toolbar. When working on smaller screens like 15 inch laptop that would be very handy. Or add a shortcut for "TAB" key to hide all toolbars (left, right, top, bottom) temporarily while staying in the same breakpoint (the same way it is done in photoshop). This would be much quicker than toggling the preview on and off. The preview is just taking too much time when you need to sweep your breakpoint elements and go quick over them.