One of the principles of good design is discoverability: it should be easy for users to discover what the program can do just by fooling around.

Menus and toolbars add discoverability: they don’t interfere if users don’t care about them but they’re always there, visible, for users to try out new features of the program.

Emacs has poor discoverability. Most of the work is being done with arbitrary keystrokes and obscure lisp functions. The only way to find out what a given keystroke or lisp function does is by reading manuals.

This is efficient for experienced users but presents a very high barrier to entry for new users.

There are two problems:

It would help discoverability if users could easily find those 2 things out. Here enters my idea: we need to add a new window that will list all keystrokes that are reachable from a given point.

Normally it would be empty. When users presses “Alt” key it would list all keystrokes that start with “Alt” key. Entries should be sorted in the order of usefulness.

That way users could see what a given keystroke does and with time learn other useful keystroke by looking at the list of available options.

This window could be small, permanent window (with the ability to hide/show it) or something that only pops-up when needed (similar to how the auto-completion usually works). This idea is not limited to Emacs - many programs implement key bindings as a short-cut for frequently used functions and could benefit from a system like this.