[libhandy] preferences-page: Add a private vertical adjustment getter

[Alexander Mikhaylenko <alexm src gnome org>]

commit 728748ac9046de0f0f42a179513a535bd3cae359
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Wed Jun 3 21:36:29 2020 +0200

    preferences-page: Add a private vertical adjustment getter
    
    This is needed to automatically scroll to a given preference since
    HdyPreferencesPage doesn't inherit from GtkScrolledWindow anymore but
    contain one instead.

 src/hdy-preferences-page-private.h |  2 ++
 src/hdy-preferences-page.c         | 12 ++++++++++++
 2 files changed, 14 insertions(+)
---
diff --git a/src/hdy-preferences-page-private.h b/src/hdy-preferences-page-private.h
index ad095480..a93ccfd9 100644
--- a/src/hdy-preferences-page-private.h
+++ b/src/hdy-preferences-page-private.h
@@ -10,6 +10,8 @@
 
 G_BEGIN_DECLS
 
+GtkAdjustment *hdy_preferences_page_get_vadjustment (HdyPreferencesPage *self);
+
 void hdy_preferences_page_add_preferences_to_model (HdyPreferencesPage *self,
                                                     GListStore         *model);
 
diff --git a/src/hdy-preferences-page.c b/src/hdy-preferences-page.c
index 6fe0a2d6..14089ede 100644
--- a/src/hdy-preferences-page.c
+++ b/src/hdy-preferences-page.c
@@ -326,6 +326,18 @@ hdy_preferences_page_set_title (HdyPreferencesPage *self,
   g_object_notify_by_pspec (G_OBJECT (self), props[PROP_TITLE]);
 }
 
+GtkAdjustment *
+hdy_preferences_page_get_vadjustment (HdyPreferencesPage *self)
+{
+  HdyPreferencesPagePrivate *priv;
+
+  g_return_val_if_fail (HDY_IS_PREFERENCES_PAGE (self), NULL);
+
+  priv = hdy_preferences_page_get_instance_private (self);
+
+  return gtk_scrolled_window_get_vadjustment (priv->scrolled_window);
+}
+
 /**
  * hdy_preferences_page_add_preferences_to_model: (skip)
  * @self: a #HdyPreferencesPage