GtkWindow::hide from GladeXML ?

Using http://gtk.php.net/manual/en/tutorials.helloadvanced.php
Example 3.1. The full program
At the end of the login function, the comments effectively say I would need to use "hide" because Gtk::main_quit() will quit the entire app.
        //No error. You would need to hide the dialog now
        //instead of destroying it (because when you destroy it,
        //Gtk::main_quit() gets called) and show the main window
        $wnd->destroy();

$wnd is a GtkWindow and $wnd->hide() works if I replace $wnd->destroy().

Now if I instead use a .glade file to create my GtkWindow or even a GtkDialog (which is a GtkWindow according to the hierarchy), how can I call "hide"?

	public function __construct(){
		$this->gladeGUI = new GladeXML(dirname(__FILE__) . '/login.glade');
		$this->gladeGUI->signal_autoconnect_instance($this);
	}

	public function onCancel(){
		$this->gladeGUI->hide();//PHP Fatal error:  Call to undefined method GladeXML::hide()
	}

onCancel is called, so I know that the object oriented autoconnect worked.
I can see that $this->gladeGUI is an object of type GladeXML, but since it displays a GtkWindow, how can I call "hide" on it?
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