In a view other than "Full Screen", the "F9" key will toggle the Mneu bar and 'F8" will toggle the Tool Bars. If in the "Full Screen: mode the "Esc" may allow return to a non-Full Screen view.
I note that the F9 keypress is ignored until a couple of seconds has elapsed after a F8 or F10 keypress! So scanning through the function keys didn't help me.
George Kaiser