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

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

function getScrollX() {
  var scrOfX = 0
  if( typeof( window.pageYOffset ) == 'number' ) {
    //Netscape compliant
    scrOfX = window.pageXOffset;
  } else if( document.body && ( document.body.scrollLeft || document.body.scrollTop ) ) {
    //DOM compliant
    scrOfX = document.body.scrollLeft;
  } else if( document.documentElement && ( document.documentElement.scrollLeft || document.documentElement.scrollTop ) ) {
    //IE6 standards compliant mode
    scrOfX = document.documentElement.scrollLeft;
  }
  return scrOfX;
}
function getScrollY() {
  var scrOfY = 0;
  if( typeof( window.pageYOffset ) == 'number' ) {
    //Netscape compliant
    scrOfY = window.pageYOffset;
  } else if( document.body && ( document.body.scrollLeft || document.body.scrollTop ) ) {
    //DOM compliant
    scrOfY = document.body.scrollTop;
  } else if( document.documentElement && ( document.documentElement.scrollLeft || document.documentElement.scrollTop ) ) {
    //IE6 standards compliant mode
    scrOfY = document.documentElement.scrollTop;
  }
  return scrOfY;
}

function topToCenter(y) {
H = Wheight();
if (y>H)
 return 0;
return (((H-y)/2)+getScrollY());
}

function leftToCenter(x) {
L = Wwidth();
if (x>L)
 return 0;
return (((L-x)/2)+getScrollX());
}

function overlaySize(divID){
if (window.innerHeight && window.scrollMaxY || window.innerWidth && window.scrollMaxX) {	
    yScroll = window.innerHeight + window.scrollMaxY;
    xScroll = window.innerWidth + window.scrollMaxX - 16;
} else if (document.body.scrollHeight > document.body.offsetHeight || document.body.scrollWidth > document.body.offsetWidth){ // all but Explorer Mac
    yScroll = document.body.scrollHeight;
    xScroll = document.body.scrollWidth;
} else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
    yScroll = document.body.offsetHeight;
    xScroll = document.body.offsetWidth;
}
getObjById(divID).style.width = xScroll +  'px';
getObjById(divID).style.height = yScroll + 'px';
}