In M$ Windows, title bar usually having context menu for operations as maximize, minimize, resize and close. But there is possible to insert menu items in this context menu. If menu bar is hidden in LibreOffice, then LibreOffice can insert menu bar items into there.
Steps to Reproduce:
User Profile Reset: No
User-Agent: Mozilla/5.0 (Android 5.1.1; Mobile; rv:57.0) Gecko/57.0 Firefox/57.0
*** This bug has been marked as a duplicate of bug 113388 ***