function returnSize() {
  var myWidth = 0, myHeight = 0;
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }
  var result = new Array(myWidth,myHeight);
  return result;
}

function windowCenter(myId) {
	result=returnSize();
	var myWidth=result[0];
	var myHeight=result[1];
	var elementWidth=document.getElementById(myId).offsetWidth;
	var elementHeight=document.getElementById(myId).offsetHeight;
        var myScrollLeft=document.documentElement.scrollLeft;
	var myScrollTop=document.documentElement.scrollTop;
	var posX=myScrollLeft+myWidth-myWidth/2-elementWidth/2
	var posY=myScrollTop+myHeight-myHeight/2-elementHeight/2;
	document.getElementById(myId).style.left=posX+"px";
	document.getElementById(myId).style.top=posY+"px";
	document.getElementById(myId).style.position="absolute";
	document.getElementById(myId).style.display="block";
}