it blinks as you expect, but it keeps blinking after for a few more seconds.
anyway, it starts blinking at the same time the program starts.
I used the native example before Processing 3, and I never got any lag problems.
and it worked.
To
PaulS:
(...) send a new value each time through draw(), depending on whether or not the mouse is in the square, or not.
is the idea I want to start from, for example.