if (document.images) {
        off = new Array(5)
        on = new Array(5)
        screenon = new Array(5)
	screen2on = new Array(5)
    on[1] = new Image();          
    on[1].src = "../images/home_02.gif";      //button_over-bilder
    on[2] = new Image();          
    on[2].src = "../images/map_02.gif";
    on[3] = new Image();          
    on[3].src = "../images/kontakt_02.gif";

   
     
    screenon[1] = new Image(); 
    screenon[1].src = "../images/home.gif";   //screen_over-bilder
    screenon[2] = new Image(); 
    screenon[2].src = "../images/sitemap.gif"; 
    screenon[3] = new Image(); 
    screenon[3].src = "../images/kontakt.gif"; 



    off[1] = new Image();         
    off[1].src = "../images/home_02.gif";    // button_std-bilder
    off[2] = new Image();         
    off[2].src = "../images/map_02.gif";
    off[3] = new Image();         
    off[3].src = "../images/kontakt_02.gif";


    } 

    function affi(knopfName,num) {  
        if (document.images) { 
          document[knopfName].src = on[num].src;
          document.screen.src = screenon[num].src;
        }
    }

    function obi(knopfName,num) {  
        if (document.images){
          document[knopfName].src = off[num].src;
          document.screen.src = "../images/o_nav_leer.gif"; //screen_std-bild
        }
    }