I just noticed that when a sprite with move-to behavior is initialized with a negative speed number -- it moves away from the a move-to target.
However, when max speed is updated once movement towards the target has commenced, then updating the maxspeed to a negative number causes the sprite to stop.
It seems the interpretation of a initial negative number is to move "away" from the target -- along an inverse vector; whereas once the sprite moves towards the target a negative number doesn't carry this meaning anymore.
Not sure what to make of this.
I guess, mathematically speaking having negative speed doesn't make sense, unless speed is a vector, but i think its just a scalar.
Btw, i couldn't understand why set speed (vs. set max speed) had no effect on the sprite -- when updated after move has commenced -- only an update of max speed caused the speed to change -- not sure why -- its a bit counter intuitive for me --
Perhaps, its because speed is controlled by the move algorithm, so speed only reports current speed but can't be set, whereas max speed is the max speed the sprite can reach along the vector to the target ... hmm, i guess, that's it.