function galSelectImg(idx){
    if(idx == 0){
      document.getElementById('galPImg').style.display = "none";
    }else{
      document.getElementById('galPImg').style.display = "block";
    }
    if(idx == photos.length-1){
      document.getElementById('galNImg').style.display = "none";
    }else{
      document.getElementById('galNImg').style.display = "block";
    }
    actPhotoIdx = idx;
    id = photos[idx];
    document.getElementById('img_window').innerHTML = '<a href="?img:'+id+':image:1000:1000" rel="lightbox" title=""><img style="border: 1px solid #bbb29f;" src="?img:'+id+':image:500:9999" /></a>';
  }

  function galPrevImg(){
    galSelectImg(actPhotoIdx-1);
  }

  function galNextImg(){
    galSelectImg(actPhotoIdx+1);
  }