I always forget the keybindings for the Emacs debugger. I'd like to have a small window open at the same time the debugger window opens with a list of keybindings (I'm thinking of something that would appear similar to the bottom Ediff window in this screenshot https://gpvprasad.files.wordpress.com/2009/12/ediff.png).
I was hoping a package like guide-key could perform this task but it doesn't seem possible.
What is the simplest way to make a window appear containing a concise list of keybindings for the active window?