function check_height(){
	var iframe=document.getElementById('occasions_frame');
	var height_frame=iframe.scrollTop;
	var stretch_this=document.getElementById('stretch_this');
	var height_stretch=iframe.scrollTop;
	var middle_container=document.getElementById('middle_container2');
	var height_container=iframe.scrollTop;
	
	/*
	alert(height_frame);
	alert(height_stretch);
	alert(height_container);
	*/
	//alert(scrollingDetector())
	/*
	alert(scrollingDetector('occasions_frame'));
	alert(scrollingDetector('stretch_this'));
	alert(scrollingDetector('middle_container2'));
	*/
	
	if (navigator.appName == "Microsoft Internet Explorer"){
		var scroller=stretch_this.scrollTop;
		//alert(scroller + " ms.");
	}
	else{
		var scroller=stretch_this.scrollTop;
		//alert(scroller + " ff.");
		//alert("You're at " + window.pageYOffset + " pixels.");
	}
	/*
	var height_span=document.getElementById('span_veld').clientHeight;
	if(height_span<height_content){
		document.getElementById('nav_bar').style.visibility= 'hidden';
	}
	*/
}

function scrollingDetector(){

	if (navigator.appName == "Microsoft Internet Explorer"){
		alert("You're at " + document.body.scrollTop + " pixels.");
	}
	else{
		alert("You're at " + window.pageYOffset + " pixels.");
	}

}