Have you looked at the hydra package on ELPA? It's easy to do what you
describe with `defhydra'.
Initially, it relied on the default `set-transient-map', but now it
uses `hydra-set-transient-map' (which makes some things easier).
Thanks. Hydra is at the top of my list for new packages to work with; I just watched your London talk on it which was very clear.
It would be nice if you could also offer a mini-hydra like your original prototype which would be less than say 100 lines and would