var helpWindow;
    var settingsWindow;
    
    function mouseoverButton(button)
    {
      button.style.borderStyle='double';
      button.style.backgroundColor='#9999ff';
      button.style.color='#333333';
      button.style.cursor='hand';
    }

    function mouseoutButton(button)
    {
      button.style.backgroundColor='#6666cc';
      button.style.color='#ffff00';
      button.style.cursor='pointer';
    }

    function popupHelp(page)
    {
      if (!helpWindow || helpWindow.closed)
      {
        // open a new help window
        switch (page)
        {
          case('recd_viewer')  : var width = 680; var height = 440; break;
          case('give_feedback'): var width = 680; var height = 600; break;
          default:
        }
        
        var url      = "help/" + page + ".html";
        var left     = parseInt((screen.availWidth / 2) - (width / 2));
        var top      = parseInt((screen.availHeight / 2) - (height / 2));
        var features = "width=" + width + ",height=" + height + 
                       ",left=" + left  + ",top="    + top + 
                       ",screenX=" + left + ",screenY=" + top; // +
//                       ",resizable, scrollbars";
        
        helpWindow = window.open(url, "help", features);

        helpWindow.focus();
      }
      else
      {
        // bring the existing help window to the front
        helpWindow.focus();
      }
    }

    function popupSettings()
    {
      if (!settingsWindow || settingsWindow.closed)
      {
        // open a new settings window
        var width = 420; var height = 420;
        
        var url      = "fb_settings.php";
        var left     = parseInt((screen.availWidth / 2) - (width / 2));
        var top      = parseInt((screen.availHeight / 2) - (height / 2));
        var features = "width=" + width + ",height=" + height + 
                       ",left=" + left  + ",top="    + top + 
                       ",screenX=" + left + ",screenY=" + top +
                       ",resizable, scrollbars";
        
        settingsWindow = window.open(url, "settings", features);

        settingsWindow.focus();
      }
      else
      {
        // bring the existing settings window to the front
        settingsWindow.focus();
      }
    }