From d50aba3e509185e51ce4000147eeb335e693ab6a Mon Sep 17 00:00:00 2001
From: Richard Hughes <richard hughsie com>
Date: Fri, 3 Mar 2017 22:17:58 +0000
Subject: [PATCH 2/3] trivial: Add a switch_from() vfunc

---
 src/gs-page.c  | 27 ++++++++++++++++++++-------
 src/gs-page.h  |  2 ++
 src/gs-shell.c |  6 ++++++
 3 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/src/gs-page.c b/src/gs-page.c
index eed74fd..a5cf904 100644
--- a/src/gs-page.c
+++ b/src/gs-page.c
@@ -610,14 +610,27 @@ void
 gs_page_switch_to (GsPage *page,
                    gboolean scroll_up)
 {
-	GsPageClass *klass;
-
-	g_return_if_fail (GS_IS_PAGE (page));
-
-	klass = GS_PAGE_GET_CLASS (page);
-	g_assert (klass->switch_to != NULL);
+	GsPageClass *klass = GS_PAGE_GET_CLASS (page);
+	GsPagePrivate *priv = gs_page_get_instance_private (page);
+	priv->is_active = TRUE;
+	if (klass->switch_to != NULL)
+		klass->switch_to (page, scroll_up);
+}
 
-	klass->switch_to (page, scroll_up);
+/**
+ * gs_page_switch_from:
+ *
+ * Pure virtual method that subclasses have to override to show page specific
+ * widgets.
+ */
+void
+gs_page_switch_from (GsPage *page)
+{
+	GsPageClass *klass = GS_PAGE_GET_CLASS (page);
+	GsPagePrivate *priv = gs_page_get_instance_private (page);
+	priv->is_active = FALSE;
+	if (klass->switch_from != NULL)
+		klass->switch_from (page);
 }
 
 void
diff --git a/src/gs-page.h b/src/gs-page.h
index 1d5c64f..62d224f 100644
--- a/src/gs-page.h
+++ b/src/gs-page.h
@@ -44,6 +44,7 @@ struct _GsPageClass
 						 GsApp		 *app);
 	void		(*switch_to)		(GsPage		 *page,
 						 gboolean	  scroll_up);
+	void		(*switch_from)		(GsPage		 *page);
 	void		(*reload)		(GsPage		 *page);
 	gboolean	(*setup)		(GsPage		 *page,
 						 GsShell	*shell,
@@ -81,6 +82,7 @@ void		 gs_page_shortcut_remove		(GsPage		*page,
 							 GCancellable	*cancellable);
 void		 gs_page_switch_to			(GsPage		*page,
 							 gboolean	 scroll_up);
+void		 gs_page_switch_from			(GsPage		*page);
 void		 gs_page_reload				(GsPage		*page);
 gboolean	 gs_page_setup				(GsPage		*page,
 							 GsShell	*shell,
diff --git a/src/gs-shell.c b/src/gs-shell.c
index 6303f33..5dff5c9 100644
--- a/src/gs-shell.c
+++ b/src/gs-shell.c
@@ -78,6 +78,7 @@ typedef struct
 	gchar			*events_info_uri;
 	gboolean		 profile_mode;
 	gboolean		 in_mode_change;
+	GsPage			*page_last;
 } GsShellPrivate;
 
 G_DEFINE_TYPE_WITH_PRIVATE (GsShell, gs_shell, G_TYPE_OBJECT)
@@ -360,6 +361,10 @@ gs_shell_change_mode (GsShell *shell,
 				!g_queue_is_empty (priv->back_entry_stack));
 
 	priv->in_mode_change = TRUE;
+
+	if (priv->page_last)
+		gs_page_switch_from (priv->page_last);
+	g_set_object (&priv->page_last, page);
 	gs_page_switch_to (page, scroll_up);
 	priv->in_mode_change = FALSE;
 
@@ -1898,6 +1903,7 @@ gs_shell_dispose (GObject *object)
 	g_clear_object (&priv->plugin_loader);
 	g_clear_object (&priv->header_start_widget);
 	g_clear_object (&priv->header_end_widget);
+	g_clear_object (&priv->page_last);
 	g_clear_pointer (&priv->pages, (GDestroyNotify) g_hash_table_unref);
 	g_clear_pointer (&priv->events_info_uri, (GDestroyNotify) g_free);
 	g_clear_pointer (&priv->modal_dialogs, (GDestroyNotify) g_ptr_array_unref);
-- 
2.9.3