document.onkeydown = function(){

if(window.event && window.event.keyCode == 116)
        {     window.event.keyCode = 505;   }

if(window.event && window.event.keyCode == 505)
        {   return false;   }
}

function chkheight(ht)
{
	var parentDocument = window.parent.document;
      	parentDocument.getElementById('topimg').src="images/topaboutust.jpg";
		parentDocument.getElementById('botimg').src="images/botimg.gif";
		parentDocument.getElementById("content").height = ht+'px';
		parentDocument.getElementById("director1").style.display ="none";
}