If menu bar is hidden, especially user enabled Notebookbar --> Tabbed / Contextual single, and user don’t want to show menu bar all the time (except clicking Hamburger button -> Menubar), for the ease-of-use purpose, LibreOffice could making it available if Alt key pressed. This way should be works until the following cases:
• A menu item from Menubar is clicked;
• User click a place other than Menubar;
• A dialog (such as Open file, Customize, Options) is showing.
Steps to Reproduce:
User Profile Reset: No
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0
*** This bug has been marked as a duplicate of bug 107358 ***