function show () {
  if (document.getElementById)
    document.getElementById("nav_help").style.visibility = "visible";
}

function hide () {
  if (document.getElementById)
    document.getElementById("nav_help").style.visibility = "hidden";
   
}
//fullscreen
function full(url)
  {
    window.open(url,"","fullscreen");
  }
//auswahl zeigen
function verstecke1() {
document.getElementById("popup1").style.visibility = 'hidden';
}
function zeigen1() {
document.getElementById("popup1").style.visibility = 'visible';
document.getElementById("popup2").style.visibility = 'hidden';
document.getElementById("popup3").style.visibility = 'hidden';
}
function verstecke2() {
document.getElementById("popup2").style.visibility = 'hidden';
}
function zeigen2() {
document.getElementById("popup2").style.visibility = 'visible';
document.getElementById("popup1").style.visibility = 'hidden';
document.getElementById("popup3").style.visibility = 'hidden';
}
function verstecke3() {
document.getElementById("popup3").style.visibility = 'hidden';
}
function zeigen3() {
document.getElementById("popup3").style.visibility = 'visible';
document.getElementById("popup1").style.visibility = 'hidden';
document.getElementById("popup2").style.visibility = 'hidden';
}
function verstecke4() {
document.getElementById("popup4").style.visibility = 'hidden';
}
function zeigen4() {
document.getElementById("popup4").style.visibility = 'visible';
}
function verstecke5() {
document.getElementById("popup5").style.visibility = 'hidden';
}
function zeigen5() {
document.getElementById("popup5").style.visibility = 'visible';
}
function verstecke6() {
document.getElementById("popup6").style.visibility = 'hidden';
}
function zeigen6() {
document.getElementById("popup6").style.visibility = 'visible';
}