//Layersteuerungen
  function showhide(element,element2,obj2){
    obj = document.getElementById(element);
    objx = document.getElementById(element2);
    if(obj.style.visibility == "hidden"){
      obj.style.visibility = "visible";
      obj.style.display = "block";
      if(obj2.checked == false)
        obj2.checked = true;
    }
    else{
      obj.style.visibility = "hidden";
      obj.style.display = "none";
    }
    if(objx.style.visibility == "hidden"){
      objx.style.visibility = "visible";
      objx.style.display = "block";
      if(obj2.checked == false)
        obj2.checked = true;
    }
    else{
      objx.style.visibility = "hidden";
      objx.style.display = "none";
    }
  }

//Window popup
function show_large_image (link) {
  popup = window.open(link, "largeimage", "width=660,height=440,left=100,top=200");
  popup.focus();
}


function hide_sky_box(){
  document.getElementById('overlay_sky').style.visibility='hidden';
  document.getElementById('sky_box').style.visibility='hidden';
}


function show_sky_box(){
  document.getElementById('overlay_sky').style.visibility='visible';
  document.getElementById('sky_box').style.visibility='visible';
}