You will need to install a user script manager extension to install this script.
Experimental script for Firefox to get fixed position elements like menu bars out of your way. On most sites, setting them to Static will return them to their normal positions. In some cases, you may need to hide them if that doesn't work.
Note: If the site uses a custom context menu, this script backs off and does not modify the context menu.
Note: I don't know how to change the position of the new items on the menu.
In about:config, double-click the
dom.menuitem.enabled preference to switch it to true if you want user scripts and website scripts to be able to add items to the context menu. (Ref. https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/contextMenu#browser_compatibility )