function _fadeOut(eId) {
	new Effect.Opacity(eId,
	{ duration:0.4,
	  transition: Effect.Transitions.linear,
	  from: 1.0, to: 0.0 });
}

function _fadeIn (eId) {
	new Effect.Opacity(eId,
	{ duration:0.4,
	  transition: Effect.Transitions.linear,
	  from: 0.0, to: 1.0 });
}