function tausche(btnnr,val) {
    var src=imgpath + "\/btn_"+btnnr + "_";
    if(val)
	src+="0"
    else
	src+="1";
    src+=".gif";
    document.getElementsByName("btn_" + btnnr)[0].src=src;
    if(val)
      if (btnnr==1 || btnnr==4) // nur vorhandene untermenüs zeign!
        sichtbar(false,btnnr);
    if (btnnr==1 || btnnr==4) // nur vorhandene untermenüs zeign!
      show(val,btnnr);
}
function sichtbar(val,btnnr) {
    if(val)
       document.getElementById("id" + btnnr).style.visibility="visible";
    else
       document.getElementById("id" + btnnr).style.visibility="hidden";
    event.cancelbubble=true;
}
function show(val,btnnr){
  if(!val)
    document.getElementById("id" + btnnr).style.visibility="visible";
}