function iFrameHeight(extraHeight) {
	  var h = 0;
	  if ( !parent.document.all ) {               
		   //h = parent.document.getElementById('mainContent').body.scrollHeight;
			//h = document.getElementById('mainContent').contentWindow.document.scrollHeight;
			//h= window.innerHeight + window.scrollMaxY
			//alert(h);
		   parent.document.getElementById('mainContent').style.height = '2000px' ;               
	  } else if( parent.document.all ) {
		   h = parent.document.frames('mainContent').document.body.scrollHeight;
		   parent.document.all.mainContent.style.height =  (h + extraHeight) + 'px' ;
	  }
}