[gnome-control-center] wacom: Fix compile-time warning

[Bastien Nocera <hadess src gnome org>]

commit 60ad6a35b40024745fe500d42aa7a56537a77ed7
Author: Bastien Nocera <hadess hadess net>
Date:   Wed Jun 7 18:16:48 2017 +0200

    wacom: Fix compile-time warning
    
    expected ‘GtkWidget * {aka struct _GtkWidget *}’ but argument is of type ‘CcWacomNavButton * {aka struct 
_CcWacomNavButton *}’

 panels/wacom/cc-wacom-nav-button.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/panels/wacom/cc-wacom-nav-button.c b/panels/wacom/cc-wacom-nav-button.c
index eda208e..ae7a89d 100644
--- a/panels/wacom/cc-wacom-nav-button.c
+++ b/panels/wacom/cc-wacom-nav-button.c
@@ -72,7 +72,7 @@ cc_wacom_nav_button_update (CcWacomNavButton *nav)
 
        g_assert (num_pages >= 1);
 
-       gtk_revealer_set_reveal_child (GTK_REVEALER (gtk_widget_get_parent (nav)),
+       gtk_revealer_set_reveal_child (GTK_REVEALER (gtk_widget_get_parent (GTK_WIDGET (nav))),
                                       num_pages > 1);
 
        current_page = gtk_notebook_get_current_page (GTK_NOTEBOOK (priv->notebook));