[FF] How to hide X-Notifier statusbar icon/toolbar

To hide X-Notifier statusbar icon
   X-notifier options -> General -> Uncheck 'Show statusbar icon'

Note: The X-Notifier statusbar icon, at bottom of Firefox window,
is different from the main X-Notifier icon that is shown in toolbars at top of window.

To hide X-Notifier Toolbar

Mac user:
   Firefox menu -> View ->  Toolbars -> Uncheck 'X-notifier Toolbar'

Windows:
   Using the Firefox 'classic' menubar:  View -> Toolbars -> Uncheck 'X-notifier Toolbar')

Using the new, orange "Firefox" menu button: 
   Click "Firebox" button -> (hover over) Options -> Uncheck 'X-notifier Toolbar'

Note:  In Windows, newer installations of Firefox replace the 'classic' menu bar with an orange 'Firefox' button.
You can show the 'classic' menu bar instead of the orange button... just as you can show/hide the X-Notifier Toolbar.
To toggle between the 'classic' menubar and the 'orange button'... just choose to show/hide the 'Menu Bar'.