Hi I am trying to make a Behavior, which contains the last pressed key and the distance the mouse traveled since the key was pressed. I programmed this function: charAndRelativeMousePos :: Anim (Maybe (Char, (Double, Double))) charAndRelativeMousePos u = scanlB (\r _ -> r) (pure Nothing) (snapshotWith char (mousePosition u) (keyAction u)) where char (_, Char ch) m = (\newMouse -> Just (ch, newMouse - m)) <$> mousePosition u char _ _ = pure Nothing Unfortunately it is not working. If I move the mouse before pressing a key, then it takes a long time before recognizing the first key-press. And it only recognizes the first key-press, never the second, nor third, ... What am I doing wrong ? I think maybe it has something to do me using "mousePosition u" twice. Am I hanging on to tons of mouse-position, due to the second use of mousePosistion ? A complete program using the charAndRelativeMousePos function can be seen here http://hpaste.org/fastcgi/hpaste.fcgi/view?id=3062#a3062 . Greetings, Mads Lindstrøm