var TimeToFade = 500.0;

function fade(eid)
{
	var element = document.getElementById(eid);
	
	// make this element exists
	if(element == null)
		return;
	
	if(element.FadeState == null) {
		if(element.style.opacity == null
			|| element.style.opacity == ''
			|| element.style.opacity == '1') {
			element.FadeState = 2;
		}
		else {
			element.FadeState = -2;
		}
	}
	
	if(element.FadeState == 1 || element.FadeState == -1) {
		element.FadeState = element.FadeState == 1 ? -1 : 1;
		element.FadeTimeLeft = TimeToFade - element.FadeTimeLeft;
	}
	else {
		element.FadeState = element.FadeState == 2 ? -1 : 1;
		element.FadeTimeLeft = TimeToFade;
		setTimeout("animateFade(" + new Date().getTime()
			+ ",'" + eid + "')", 33);
	} 
}

function animateFade(lastTick, eid)
{ 
	var curTick = new Date().getTime();
	var elapsedTicks = curTick - lastTick;
	
	var element = document.getElementById(eid);
	
	if(element.FadeTimeLeft <= elapsedTicks) {
		element.style.opacity = element.FadeState == 1 ? '1' : '0';
		element.style.filter = 'alpha(opacity = '
			+ (element.FadeState == 1 ? '100' : '0') + ')';
		element.FadeState = element.FadeState == 1 ? 2 : -2;
		return;
	}
	
	element.FadeTimeLeft -= elapsedTicks;
	var newOpVal = element.FadeTimeLeft/TimeToFade;
	
	if(element.FadeState == 1) {
		newOpVal = 1 - newOpVal;
	}
	
	element.style.opacity = newOpVal;
	element.style.filter =
	  'alpha(opacity = ' + (newOpVal*100) + ')';
	
	setTimeout("animateFade(" + curTick
	  + ",'" + eid + "')", 33);
}