[gnome-control-center] wacom: Fix crasher using link to display panel

[Bastien Nocera <hadess src gnome org>]

commit 5a2b4112553f2b910c559a7624c16adfaa9d6d3d
Author: Bastien Nocera <hadess hadess net>
Date:   Fri May 25 12:14:27 2012 +0100

    wacom: Fix crasher using link to display panel
    
    ->panel was never set within the page object.

 panels/wacom/cc-wacom-page.c  |    2 ++
 panels/wacom/cc-wacom-panel.c |    2 ++
 2 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/panels/wacom/cc-wacom-page.c b/panels/wacom/cc-wacom-page.c
index a0cff9a..f3840ef 100644
--- a/panels/wacom/cc-wacom-page.c
+++ b/panels/wacom/cc-wacom-page.c
@@ -849,6 +849,7 @@ cc_wacom_page_dispose (GObject *object)
 		priv->builder = NULL;
 	}
 
+	priv->panel = NULL;
 
 	G_OBJECT_CLASS (cc_wacom_page_parent_class)->dispose (object);
 }
@@ -1129,6 +1130,7 @@ cc_wacom_page_new (CcWacomPanel   *panel,
 	page = g_object_new (CC_TYPE_WACOM_PAGE, NULL);
 
 	priv = page->priv;
+	priv->panel = panel;
 
 	cc_wacom_page_update_tools (page, stylus, eraser, pad);
 
diff --git a/panels/wacom/cc-wacom-panel.c b/panels/wacom/cc-wacom-panel.c
index 087d1b6..10b0df6 100644
--- a/panels/wacom/cc-wacom-panel.c
+++ b/panels/wacom/cc-wacom-panel.c
@@ -294,6 +294,8 @@ cc_wacom_panel_switch_to_panel (CcWacomPanel *self,
 	CcShell *shell;
 	GError *error = NULL;
 
+	g_return_if_fail (self);
+
 	shell = cc_panel_get_shell (CC_PANEL (self));
 	if (cc_shell_set_active_panel_from_id (shell, panel, NULL, &error) == FALSE)
 	{