function getScreenCenterY() {
var y = 0;

y = getScrollOffset()+(getInnerHeight()/2);

return(y);
}

function getScreenCenterX() {
return(document.body.clientWidth/2);
}

function getInnerHeight() {
var y;
if (self.innerHeight) // all except Explorer
{
y = self.innerHeight;
}
else if (document.documentElement && document.documentElement.clientHeight)
// Explorer 6 Strict Mode
{
	y = document.documentElement.clientHeight;
}
else if (document.body) // other Explorers
{
	y = document.body.clientHeight;
}
return(y);
}