Keyboard Menu/App Key
What's the Menu Key For
The ▤ Menu key, also known as Apps key, is meant to be a application-specific context menu key.
In folder viewer (Windows Explorer), after you selected a item, you can press ▤ Menu r to rename, ▤ Menu d to delete, ▤ Menu p to show info/properties, etc.
In web browsers, after you made a text selection, press ▤ Menu c to copy, and ▤ Menu p to paste. Also works in terminal and most other apps.
Pressing Shift+F10 is the same as menu key in most applications.
As Mouse Right Button
The ▤ Menu key's function is similar to mouse's right button.
Note: press the ▤ Menu key is not equivalent to pressing the right mouse button. For example, in a browser, pressing right mouse button on a link pops up a context menu for that link. But press ▤ Menu doesn't show the same context menu. You need first to put focus on the link (by pressing Tab), then press ▤ Menu.
Invasion of the FN key
FN key is like a dead horse squatting in front yard.
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 Operating System. If you don't like its preset multimedia functions, it becomes a useless key on one of the most important spot.
Menu Key Use in Emacs
Emacs: Bind Menu/App Key
Menu Key Gone
The menu key started to disappear on keyboards around 2010s. For example, Logitech Non-Gaming Keyboards don't have them, Chromebook Keyboard doesn't have them, and many laptop don't have them. Even half of Microsoft Keyboards, don't have them, especially those for mobile phone or portable computers.
The ▤ Menu key is invented by Microsoft. It first appeared on the Microsoft Natural Keyboard in 1994. Typically, it is only on the right side besides Control key.