Tweak the Gestures Overlay demo. This shortens the fade duration to make it...

Tweak the Gestures Overlay demo. This shortens the fade duration to make it more usable and also adds a longer pause before the fade. This change also introduce a new compile-time setting to decide whether or not the overlay should steal the events from the underlying ListView. It is now off by default, per discussion with hackbod. It feel a little bit better but it may vary from user to user so studies will be necessary.