If "Use headset controls" is off doubleTwist will not receive headset events if doubleTwist has not been launched during the current OS session (i.e. after boot). However, even when the setting is off, doubleTwist will receive headset events if doubleTwist was the last music app to be launched. Once another music app is launched and asks the Android OS to be the primary recipient of headset events, doubleTwist will no longer receive and respond to these events.