function CalculateHeight()
{
 if(window.innerHeight)
  return(window.innerHeight);
 if(document.documentElement.clientHeight)
 {
  if(document.documentElement.clientHeight>0)
   return(document.documentElement.clientHeight);
 }
 if(document.body.clientHeight)
  return(document.body.clientHeight);
 return(800);
}