//// code for pop-up menus



// how it works:

//  When the mouse passes over a menu-inducing navigation button, it calls

//   show_menu_exclusive() to swap the button image, open that button's pop-up menu,

//   and close any others that might be open.

//  When the mouse leaves the nav button, it starts a delayed restore of the button image

//   and closing of that pop-up menu by calling start_delayed_hide_menu(). The closing

//   is delayed because the mouse might be entering the pop-up menu. If not, then the menu

//   will either be closed by the delayed call to do_delayed_hide_menu(), or by entering

//   a different navigation button.

//  When the mouse enters a pop-up menu button, it cancels the delayed close of that

//   pop-up menu with cancel_delayed_hide_menu().

//  When the mouse leaves a pop-up menu button, it starts the delayed close.



// Copyright (C) 2002 Robert J. Wilt



//// globals



// variable records which menu is currently open

var open_menu = "";



// timer for delayed hide

var timerid = null;



// browser

var NS = (navigator.appName == "Netscape");

IE4 = document.all; NS4 = document.layers; NS6a = document.getElementById;

if (NS6a && NS) {NS6=1;} else {NS6=0;}

if ((IE4) || (NS4) || (NS6)) {dhtml=1;}



//// functions



// show main nav mouseover and corresponding pop-up menu (immediately hide previous, if any)

//

function show_menu_exclusive(menuname) {



  if (timerid != null) {        // cancel any delayed hides

    clearTimeout (timerid);

    timerid = null;

  }



  if (open_menu == menuname)  // return if this menu already open

    return;



  if (open_menu != "") {      // hide the old pop-up menu

    var oldmenulayer = open_menu + "menu";

    MM_showHideLayers(oldmenulayer,'','hide')

  }



  if (menuname != "") {       // show the new pop-up menu

    var menulayer = menuname + "menu";

    MM_showHideLayers(menulayer,'','show');

  }



  // record the open menu

  open_menu = menuname;

}



// start delayed main nav image restoration and pop-up menu hiding

//

function start_delayed_hide_menu() {

  timerid = setTimeout("do_delayed_hide_menu()", 200); // last arg is delay in milliseconds

}



// cancel delayed main nav image restoration and pop-up menu hiding

//

function cancel_delayed_hide_menu() {

  if (timerid != null) {

    clearTimeout (timerid);

    timerid = null;

  }

}



// perform delayed main nav image restoration and pop-up menu hiding

//

function do_delayed_hide_menu() {

  show_menu_exclusive("");

}