It seems that going from Event(1) -> Behavior(2) -> Event(3) -> Behavior(4) is broken: http://trac.haskell.org/reactive/ticket/13 The first event(1), is for example a keyPressed, which is accumB'd into a Behavior(2). Then that Behavior is snapshotted(3) against a regular interval ticker (atTimes [0, gap..]), and then "stepper" is used to convert it to a behavior(4) again. The whole behavior(4) is broken and does not change at all, while the intermediate behavior(2) is just fine. Any idea what could cause this? Eyal