/*
 * from http://www.quirksmode.org/js/findpos.html
 * returns the x coordinate of supplied object's top-left corner
 */
 function findPosX(obj)
{
	var curleft = 0;
	if (obj.offsetParent)
	{
		while (obj.offsetParent)
		{
			curleft += obj.offsetLeft
			obj = obj.offsetParent;
		}
	}
	else if (obj.x)
		curleft += obj.x;
	return curleft;
}

/*
 * from http://www.quirksmode.org/js/findpos.html
 * returns the y coordinate of supplied object's top-left corner
 */
function findPosY(obj) {
	var curtop = 0;
	if (obj.offsetParent)
	{
		while (obj.offsetParent)
		{
			curtop += obj.offsetTop
			obj = obj.offsetParent;
		}
	}
	else if (obj.y)
		curtop += obj.y;
	return curtop;
}

/*
 * modified from http://www.quirksmode.org/js/findpos.html
 * Sets the submenu position relative to its main menu counterpart
 */
function setSubmenuPos(obj,lyr) {
    //offsets from top left corner of parent menu item, in em
	topOffset=1.3; //em
	leftOffset=0;  //em

	var newX = findPosX(obj);
	var newY = findPosY(obj);
	var x = document.getElementById(lyr);
//	x.style.top  = newY + 'px';
//	x.style.left = newX + 'px';
	x.style.top  = '0px';
	x.style.left  = '0px';

    x.style.margin=topOffset+"em 0 0 "+leftOffset+"em";
}

/*
 * Shows the submenu with the id submenu_x
 * Assumes that the parent menu item has id menu_x
 */
function showMenu(menuNum) {
  if(document.getElementById("submenu_"+menuNum)) {
    document.getElementById("submenu_"+menuNum).style.display="block";
  }
}

/*
 * Hides all submenus
 * Assumes that the submenu has the id submenu_x
 * Assumes that the parent menu item has id menu_x
 * Assumes that parent menu items are numbered sequentially from zero
 */
function hideMenus() {
  var count=0;
  while(document.getElementById("menu_"+count)) {
    if(document.getElementById("submenu_"+count)) {
      document.getElementById("submenu_"+count).style.display="none";
    }
    count++;
  }
}

function setUpMenus() {
  i=0;
  while(document.getElementById("menu_"+i)) {
    if(document.getElementById("submenu_"+i)) {
      obj=document.getElementById("menu_"+i);
      setSubmenuPos(obj,"submenu_"+i);
    }
    i++;
  }
  hideMenus();
}