the ▤ Menu key is just fantastic. Now, in Firefox, you can press 【▤ Menu c】 to copy, and 【▤ Menu p】 to paste. Also works in terminal and most other apps.
In desktop (file manager), you can press 【▤ Menu r】 to rename, 【▤ Menu d】 to delete, 【▤ Menu p】 to show info/properties, etc.
this is particularly nice when your keyboard has a nice positioned ▤ Menu key.
On some Batman Keyboards, you can set a thumb key to do ▤ Menu.
or, you can make your Caps Lock to be the ▤ Menu key.
xmodmap. 〔➤ Linux: xmodmap Tutorial ⌨〕.
When you buy a keyboard, never get one that has Fn key in place of ▤ Menu key. Because, the Fn key is hardwired, you cannot remap in OS. If you don't like its preset multimedia functions, it becomes a useless key on one of the most important spot. Like, a dead horse squatting in front yard.
See: Emacs: How to Define Menu/App Keys.