You guys are way ahead of me (not unexpectedly, of course).

What I did was a generalization of the method EnglishBob described. Or a simpler version of lesbentley's, depending on how you prefer to look at it. I didn't interpolate between the different morphs, just stacked them on top of each other. So in my version of lesbentley's demo, the boxes would just stay up and never go back down.

More specifically: I used three morphs A, B and C for that knee bend, all of them with enforced limits of 0 and 1 and slaved to the shin's x-rotate channel with factors of 0.011111, 0.033333 and 0.033333, respectively. Then I created a channel called 'one' in the BODY actor with a fixed value of 1. I slaved the B morph to that with a factor of -3 and the C morph with -4. So between 0 and 90 degrees, only the A morph is active. From 90 degrees on, A stays frozen at 1 and B reaches its lower limit of 0, so it start becoming effective. Then at 120 degrees, B is at 1 as well and C starts to take effect.

PS: I love those blinds, by the way.

-- I'm not mad at you, just Westphalian.