function display(id){
document.getElementById(id).style.display = 'inline';

}
function hide(id1,id2){
document.getElementById(id1).style.display = 'none';
document.getElementById(id2).style.display = 'none';
}

function showShader() {

   var x,y;
   var test1 = document.getElementById('BodyId').scrollHeight;
   var test2 = document.getElementById('BodyId').offsetHeight
   
   if (test1 > test2) // all but Explorer Mac
   {
      x = document.getElementById('BodyId').scrollWidth;
      y = document.getElementById('BodyId').scrollHeight;
   }
   else // Explorer Mac;
        //would also work in Explorer 6 Strict, Mozilla and Safari
   {
      x = document.getElementById('BodyId').offsetWidth;
      y = document.getElementById('BodyId').offsetHeight;
   }
   
   document.getElementById('shaderdiv').style.width = (x) + "px";
   document.getElementById('shaderdiv').style.height = (y+400) + "px";
   display('shaderdiv');

}