This is the bit I do not understand about the api. In your example below:

m-processing
t-Locking
t-Waiting
t-Signalling  # if a tree signals in a forest, and noone's listening
t-Locking
t-Waiting     <<<< Point A
m-locking
m-waiting     # and again, we both wait...
[download]

At point A, t has locked the shared var and goes into the wait state.

Then m gets a timeslice, finishes processing and loops back to lock() the var. It gets the lock, but t hasn't yet released it?

Then again, whilst m is processing, the lock it acquired is still in force, so how the hell did t manage to aquire a lock and move forward to the wait/signal/lock/wait steps?

If it is possible to use this api to synchronise two threads access to a single var, I'd sure like to see it.