var screenWidth=980,screenHeight=400;
function getScreenSize(){
	if(typeof(window.innerWidth)=='number'){
		//Non-IE
		//screenWidth=window.innerWidth;
		var u=document.getElementById("dummy-width");
		screenWidth=u.offsetWidth;
		screenHeight=window.innerHeight;
	}else if(document.documentElement&&(document.documentElement.clientWidth||document.documentElement.clientHeight)){
		//IE 6+ in 'standards compliant mode'
		screenWidth=document.documentElement.clientWidth;
		screenHeight=document.documentElement.clientHeight;
	}else if(document.body&&(document.body.clientWidth||document.body.clientHeight)) {
		//IE 4 compatible
		screenWidth=document.body.clientWidth;
		screenHeight=document.body.clientHeight;
	}
}