function preload_pics() {
  var d = document;
  if (d.images) {
    if (!d.preloaded)
      d.preloaded = new Array();
    var j = d.preloaded.length;
    for (var i=0; i<arguments.length; i++) {
      // Active pic
      d.preloaded[j] = new Image();
      d.preloaded[j++].src = arguments[i];
    }
  }
}

function pic_over(name, file)
{
  if (document.images) {
    document[name].src = file;
  }
}

function pic_out(name, file)
{
  if (document.images) {
    document[name].src = file;
  }
}