// JavaScript Document
// This document contains the function for image swapping on the menu bar as well
// as for displaying, hiding submenus on mouseover
// The behaviour 
var last_submenu;
var first_submenu;

function set_last_submenu( lIndex )
{
 // This function tracks the currently selected menu item when a user has 
 // clicked on a menu item
  if( lIndex > 0)
  {
    last_submenu = lIndex;
    first_submenu = (-1) * lIndex;
  }
  else
  {
    last_submenu = 0;
    first_submenu = 0;
  }
  
}

function swap_menu_image( menu_item_no )
{
  if(menu_item_no == last_submenu)
  {
    return;
  }

  if( menu_item_no > 0 ){
    var current_item =  document.getElementById('menu_item' + menu_item_no );
    current_item.bgColor = '21439D';
    
    if( last_submenu > 0 )
    {
      var last_item =  document.getElementById('menu_item' + last_submenu );
      last_item.bgColor = '0072BB';
    }
  }
  else if(menu_item_no < 0)
  {
    last_submenu = -1*menu_item_no;
  }
}

function change_status( menu_item_no )
{
    document.getElementById('submenu0').style.display = "none";

    if( last_submenu == menu_item_no )
    {
      // exit if mouse is over same item in a row
      return;
    }
    
  	var sub_menu=document.getElementById('submenu' + menu_item_no);
  	sub_menu.style.display='inline';
  	//activate appropriate submenu
  	
  	
  	if(last_submenu >= 0)
  	{
    	var previous_submenu= document.getElementById('submenu'+last_submenu);
      previous_submenu.style.display = "none";  
      // hide previous menu
    }
    
    last_submenu = menu_item_no;	
    //keep track of current menu shown
}