Something that has been bothering since the first versions of the Otter Browser is the menu bar. When I decide to hide it, the problem will be when I give F11 to the browser to be in full screen, and then I give F11 to the screen to return to normal: the menu bar reappears mysteriously, when it should be hidden. Interestingly the option of the hidden menu bar remains set, and I need to double-click so that the bar is actually hidden again.