button1= new Image();
    button1.src = "img/nav/1b.gif"
    button1b= new Image();
    button1b.src = "img/nav/1g.gif"
    
    button2= new Image();
    button2.src = "img/nav/2b.gif"
    button2b= new Image();
    button2b.src = "img/nav/2g.gif"
    
    button3= new Image();
    button3.src = "img/nav/3b.gif"
    button3b= new Image();
    button3b.src = "img/nav/3g.gif"
        
    button4= new Image();
    button4.src = "img/nav/4b.gif"
    button4b= new Image();
    button4b.src = "img/nav/4g.gif"
    
    button5= new Image();
    button5.src = "img/nav/5b.gif"
    button5b= new Image();
    button5b.src = "img/nav/5g.gif"
    
    
    button1_en= new Image();
    button1_en.src = "img/nav/1b_en.gif"
    button1b_en= new Image();
    button1b_en.src = "img/nav/1g_en.gif"
    
    button2_en= new Image();
    button2_en.src = "img/nav/2b_en.gif"
    button2b_en= new Image();
    button2b_en.src = "img/nav/2g_en.gif"
    
    button3_en= new Image();
    button3_en.src = "img/nav/3b_en.gif"
    button3b_en= new Image();
    button3b_en.src = "img/nav/3g_en.gif"
        
    button4_en= new Image();
    button4_en.src = "img/nav/4b_en.gif"
    button4b_en= new Image();
    button4b_en.src = "img/nav/4g_en.gif"
    
    button5_en= new Image();
    button5_en.src = "img/nav/5b_en.gif"
    button5b_en= new Image();
    button5b_en.src = "img/nav/5g_en.gif"
    
    function popup (url) {
     fenster = window.open(url, "Popupfenster", "width=440,height=600,resizable=yes,scrollbars=yes");
     fenster.focus();
     return false;
    }