function getWindowSize()
{
  var w = 0;
  var h = 0;

  //IE
  if(!window.innerWidth)
  {
    //strict mode
    if(!(document.documentElement.clientWidth == 0))
    {
      w = document.documentElement.clientWidth;
      h = document.documentElement.clientHeight;
    }
    //quirks mode
    else
    {
      w = document.body.clientWidth;
      h = document.body.clientHeight;
    }
  }
  //w3c
  else
  {
    w = window.innerWidth;
    h = window.innerHeight;
  }
  
  return {width:w,height:h};
}

function getWindowCenter(width, height)
{
  var _x = 0;
  var _y = 0;
  var offsetX = 0;
  var offsetY = 0;
  
  //IE
  if(!window.pageYOffset)
  {
    //strict mode
    if(!(document.documentElement.scrollTop == 0))
    {
      offsetY = document.documentElement.scrollTop;
      offsetX = document.documentElement.scrollLeft;
    }
    //quirks mode
    else
    {
      offsetY = document.body.scrollTop;
      offsetX = document.body.scrollLeft;
    }
  }
  //w3c
  else
  {
    offsetX = window.pageXOffset;
    offsetY = window.pageYOffset;
  }

  sz = getWindowSize();
  
  _x = ((sz.width-width)/2)+offsetX;
  _y = ((sz.height-height)/2)+offsetY;
  
  return{x:_x,y:_y};
}