So the tabbed notebookbar hides the menu bar and one possible option for unhiding it temporarily is to have it respond to Alt, as it normally does when it is unhidden. This concept can be seen in Firefox.
Tomaz mentioned in bug 90195 comment 4 that he had some working code to do this, so this bug is the place to pursue this possible option of what to do with the Alt key when the menubar is hidden. The other option for the use of Alt is in bug
*** Bug 114669 has been marked as a duplicate of this bug. ***
Internet Explorer 7+ and Mozilla Firefox have already implemented this operation.
Hello Szymon Kłos,
Is it possible to add this instruction into .uno:Menubar command?
But that doesn't sound like a great idea, because it would basically prevent having Alt-access to the Tabs (as requested in bug 107344).