var currObj = ""; 

  function resize(img) {
      var div = currObj;
      var clientW = parseInt(document.body.clientWidth);
      var clientH = parseInt(document.body.clientHeight);
      var imgW = parseInt(img.width);
      var imgH = parseInt(img.height);
      var scrollTop = parseInt(document.body.scrollTop);
      div.innerHTML = "";
      div.style.left = ((clientW / 2) - (imgW/ 2)) + "px";
      div.style.top = (scrollTop + (clientH / 2) - (imgH / 2)) + "px";
      div.appendChild(img);    
      return div;
  }

  function new_window(name, src) {  
    var div = document.createElement('DIV');
    div.id = "window_"+name;
    div.onclick = function () {
      close_window(this);
    }
    div.className = "window";
    currObj = div;
    var img = document.createElement('IMG');
    img.src = src
    img.className = "preview";
    if (!img.width) {
      img.onload = function () {
        var img = this;
        div = resize(img);
      }
    } else {
      div = resize(img);
    }
    
    document.body.onclick = function () {close_window(div);}

    if (!document.getElementById('window_'+name)) {
      document.body.appendChild(div);
    }
  }
  
  function close_window(win) {
    document.body.onclick = null;
    document.body.removeChild(win);
  }