I'm ashamed to say I've been using Emacs since 1992 but I have never been able to impress into my brain anything other than the minimal set of keystrokes to do basic editing. I feel like I need to be trapped on an island where the only thing I could do was learn emacs for a bit. There's so much there to dig into.
This is why I regularly create hydras for every emacs mode that I use. That way I don't have to remember any extra keystrokes, as the hydras will remind me.
So it's sort of like a mode switch? You give the prefix, and then you can give it a whole series of commands, based on a crib sheet that it shows you, that have that common prefix - without having to retype the prefix - before passing a different key to drop out of the mode again?
That does sound potentially handy, if I have it right.
Yes, though I'd describe it more as a fully-customizable popup menu that appears when you type a certain keystroke. Once the menu appears you can type more keystrokes to perform an action or bring up another custom menu.
Also, it's possible to configure it so that there's a delay between the time you type a keystroke and the menu appears, so that if you remember the key-sequence you need to type to perform a certain action and you type it fast enough, then the menu won't pop-up, but if you forget the full sequence then you can type just the first keystroke and then wait a bit and the menu will pop up and remind you of what needs to be typed to execute the action you want.
It's super handy, and is one of my all-time-favorite emacs packages.
