var highlighted_left = "";
var highlighted_site = "";
var img_normal = "images/back_button.jpg";
var img_select = "images/back_button2.jpg";
var img_site_select = "images/back_button3.gif";

img = new Image();
function load_img (id) {
 
 img.src = "images/back_button2.jpg";
 
 highlighted_site = id;
 highlighted_left = id;
 highlight(id);
 }

function highlight (id) {
	
	if(highlighted_left) {	// wenn Button selektiert
		if(highlighted_left == id) {	// Wenn dieser Button ich bin
			if(highlighted_site == id) {	// Wenn Site-Selektion
				document.getElementById(id).style.backgroundImage = "url("+img_site_select+")";
				}
			else {
				document.getElementById(id).style.backgroundImage = "url("+img_normal+")";				
				}
				
			highlighted_left = "";
			return;
			}
		document.getElementById(id).style.backgroundImage = "url("+img_normal+")";					
		highlighted_left = "";
		}
	
	document.getElementById(id).style.backgroundImage = "url("+img_select+")";
	highlighted_left = id;
	
	}