var old_value;
	
	img1_bar = new Image();
	img1_bar.src = "../images/header_datenbank.gif";
	img1a_bar = new Image();
	img1a_bar.src = "../images/header_navred_mo10.gif";
	img2_bar = new Image();
	img2_bar.src = "../images/header_philashop.gif";	
	img2a_bar = new Image();
	img2a_bar.src = "../images/header_navgreen_mo20.gif";	
	img3_bar = new Image();
	img3_bar.src = "../images/header_quiz.gif";	
	img3a_bar = new Image();
	img3a_bar.src = "../images/header_navblue_mo30.gif";	
	img4_bar = new Image();
	img4_bar.src = "../images/header_software.gif";	
	img4_bar = new Image();
	img4_bar.src = "../images/header_navorange_mo40.gif";	
	
	function show_img(imgname,imgnumber,numbername)
	{
		old_value = parent.frametop.document.top_header.src;
		parent.frametop.document.top_header.src = imgname;
		parent.frametop.document[numbername].src = imgnumber;
		return true;	
	}
	
	function hide_img(imgnumber,numbername)
	{
		parent.frametop.document.top_header.src = old_value;
		parent.frametop.document[numbername].src = imgnumber;
		return true;
	}
	
	function show_one(imgnumber,numbername)
	{	
		parent.frametop.document[numbername].src = imgnumber;
		return true;
	}	

	function hide_one(imgnumber,numbername)
	{	
		parent.frametop.document[numbername].src = imgnumber;
		return true;
	}