function newImage(arg) {
  if (document.images) {
    rslt = new Image();
    rslt.src = arg;
    return rslt;
  }
}

function changeImages() {
  if (document.images && (preloadFlag == true)) {
    for (var i=0; i<changeImages.arguments.length; i+=2) {
      document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
    }
  }
}

var preloadFlag = false;
function preloadImages() {
  if (document.images) {
    menu_01_o = newImage("images/menu_01_o.gif");
    menu_01_d = newImage("images/menu_01_d.gif");
    menu_02_o = newImage("images/menu_02_o.gif");
    menu_02_d = newImage("images/menu_02_d.gif");
    menu_03_o = newImage("images/menu_03_o.gif");
    menu_03_d = newImage("images/menu_03_d.gif");
    menu_04_o = newImage("images/menu_04_o.gif");
    menu_04_d = newImage("images/menu_04_d.gif");
    menu_05_o = newImage("images/menu_05_o.gif");
    menu_05_d = newImage("images/menu_05_d.gif");
    preloadFlag = true;
  }
}
function open_window(html_name,w,h,window_name){
  window.open(html_name,window_name,
    "width="+w+",height="+h+",scrollbars=1,status=0,resizable=yes");
}