To switch back and forth between browser full screen and normal view (i.e., hide the menu bar) do either of the following gestures: a "touch" followed by a "tap", or a "tap" followed by a "touch".
"Touch" means you do not depress the screen (i.e., the level of contact used for scrolling). "Tap" is a full press.
A double-Tap zooms in, but that is already well known.
