/*
 * Drop Down Menu
 */
var timeout = 500;
var closetimer  = 0;
var ddmenuitem  = 0;

// open hidden layer
function mopen(id)
{
  // cancel close timer
  mcancelclosetime();
  // close old layer
  if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';

  // get new layer and show it
  ddmenuitem = document.getElementById(id);
  ddmenuitem.style.visibility = 'visible';
}

// close showed layer
function mclose()
{
  if(ddmenuitem) ddmenuitem.style.visibility = 'hidden';
}

// go close timer
function mclosetime()
{
  closetimer = window.setTimeout(mclose, timeout);
}

// cancel close timer
function mcancelclosetime()
{
  if(closetimer)
  {
    window.clearTimeout(closetimer);
    closetimer = null;
  }
}

// close layer when click-out
document.onclick = mclose;


/*
 * For mouseover on image links
 */
function roll(img_name, img_src)
{
  document[img_name].src = img_src;
}