// JavaScript Document
function startPolling(){setInterval("poll()",10)}

function poll(){

  myHeight = 0;  // var for height of browser window
  
  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;
  }

  var T= 0; // T = distance between of static ISI layer and top of browser window
	
  hoo = document.getElementById('static_ISI');
	
  while(hoo){
    T+= hoo.offsetTop;
    hoo= hoo.offsetParent;
  }
	
  if(window.pageXOffset!==undefined){
    T-= pageYOffset;
  }
  else{
    var d= document.documentElement, b=document.body;
    T-= (d.scrollTop+b.scrollTop);	// T = distance between of static ISI layer and top of browser window
  }
	
  //alert ("top of static_ISI = " + T);
  var difference = (T - myHeight); // distance between static ISI layer and height of browser window

// use the below code for debugging, this renders on the hover ISI layer
//document.getElementById('hover_ISI').innerHTML = "T = " + T + " myHeight = " + myHeight + " difference = " + difference;

 
  if (difference > -220 && difference < -55)
  {document.getElementById('hover_ISI').style.height=(difference * -1) + 'px';} // changes height of hover ISI layer relative to "difference" (or amount of scroll)
  else
  {document.getElementById('hover_ISI').style.height=50 + 'px';}// sets height of hover ISI layer
	
	// if the difference between the layers is a certain value, then show/hide layers
	if (difference <= -220) {
	document.getElementById('hover_ISI').style.visibility="hidden";
	document.getElementById('static_ISI').style.visibility="visible";
	}else{
	document.getElementById('hover_ISI').style.visibility="visible";
	document.getElementById('static_ISI').style.visibility="hidden";
	}
	
return true;
}