function ablak(){
  if ($('ablak')) document.body.removeChild($('ablak'));
  if (arguments.length == 0) return false;
  var a = document.createElement("div");
  a.className = "ablak";
  if (arguments.length > 1) a.style.width  = arguments[1]+"px";
  if (arguments.length > 2) a.style.height = arguments[2]+"px";
  a.innerHTML = "<div class='ablak_close'><a href='javascript: void(0);' onclick='ablak()'>bezár X</a></div><div class='ablak_content'>"+arguments[0]+"</div>";
  a.id = "ablak";
  document.body.appendChild(a);
  kozepre('ablak');
}
function kozepre(){
  var id = arguments.length > 0 ? arguments[0] : "ablak";
  var div = $(id);
  var viewport = document.viewport.getDimensions();
  var scroll = document.viewport.getScrollOffsets();
  div.style.left = Math.floor((viewport.width  - div.offsetWidth)  / 2) + scroll.left + "px";
  div.style.top  = Math.floor((viewport.height - div.offsetHeight) / 2) + scroll.top  + "px";
}
function ablak2(id){
  if (arguments.length == 0) return false;
  $(id).style.display = "block";
  kozepre(id);
}
function ablak2_csuk(id){
  if ($(id)) $(id).style.display = "none";
}