Movement blocking is well beyond me, but showing movement limits turned out to be fairly easy, and I thought I'd show everyone what I was doing. I've worked out how to embed a movement limit in a token, and then have the movement path change when that limit is exceeded.
Visually, it looks like this (this is not a mockup; it actually runs):
MoveLimit
It's way primitive at this point. Tokens are defaulted to 100 squares so it doesn't crash out if you move a token before you set its move limit; it only works on a square grid, and it only works in terms of squares, so it's not like "ready for prime time." However, I will continue to pursue it if other people think it might be useful!
...and, I was proud of myself for making it work. So I thought I'd preen a bit.