The CTRL-U shortcut displays the source version of the current page. In some specific situations, this feature can be useful, but not very often for regular users (in contrast to developers). Unfortunately I can't find a way to switch back from this view: Ctrl-U isn't a toggle and there's no other shortcut that could be used to display initial view again. Also, I haven't found a menu command useful in such situation. Also it is impossible to disable Firefox shortcuts selectively. Thus if you press Ctrl-U by chance then you cant view the original rendered page version and you lost what you entered in editing fields on the page. Is there a way to achieve some level of control over this unwanted "improvement"?