var displayed = null;

var LINK = "_link";

(function()
{
  if (window.addEventListener)
  {
    window.addEventListener("load", setup_drop_down_menu, false);    
  }
  else
  {
    window.attachEvent("onload", setup_drop_down_menu);
  }
})();

function setup_drop_down_menu()
{
  var divs = document.getElementById("navigation_menu").getElementsByTagName("div");
  
  for (var i = 0; i < divs.length; i++)
  {    
    setup_link(divs[i].id);
  }
}

function setup_link(div_id)
{
  var link = document.getElementById(div_id + LINK);
  
  link.onmousemove = function(){display_menu(div_id);};
  //link.onmouseout = function(){hide_displayed_menu();}
  link.onclick = function(){hide_displayed_menu();} 
}

function hide_displayed_menu()
{
  if (displayed)
  {
    displayed.style.display = 'none';
    displayed = null;
  }
}

function display_menu(id)
{
  hide_displayed_menu();

  displayed = document.getElementById(id);
  displayed.style.display = 'block';
  
  displayed.onmouseover = function(){display_menu(id);};
  displayed.onmouseout = function(){hide_displayed_menu();};    
  displayed.onclick = function(){hide_displayed_menu();};
}

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function MM_swapImgRestore() {
  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}

function MM_findObj(n, d) { //v4.01
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && d.getElementById) x=d.getElementById(n); return x;
}

function MM_swapImage() {
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}