function imgOn(imgName) {
   if (document.images) {
       document[imgName].src = eval(imgName + "on.src");
        }
}

function imgOff(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "off.src");
        }
}


img1on = new Image();
img1on.src = "img/start_navi_solar.gif";
img2on = new Image();
img2on.src = "img/start_navi_heiz.gif";
img3on = new Image();
img3on.src = "img/start_navi_luft.gif";
img4on = new Image();
img4on.src = "img/start_navi_sani.gif";


img1off = new Image();
img1off.src = "img/start_navi_solar2.gif";
img2off = new Image();
img2off.src = "img/start_navi_heiz2.gif";
img3off = new Image();
img3off.src = "img/start_navi_luft2.gif";
img4off = new Image();
img4off.src = "img/start_navi_sani2.gif";




function objekt(n, d) {
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=objekt(n,d.layers[i].document);
  if(!x && document.getElementById) x=document.getElementById(n); return x;
}

function zeige_ebene() { 
  var i,p,v,obj,args=zeige_ebene.arguments;
  for (i=0; i<(args.length-2); i+=3) if ((obj=objekt(args[i]))!=null) { v=args[i+2];
    if (obj.style) { obj=obj.style; v=(v=='show')?'visible':(v='hide')?'hidden':v; }
    obj.visibility=v; }
}