[gtkmm] Gtk::Settings: Implement StyleProvider

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 21fce1976db145889f01dae74393fdc0a60ff514
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Wed Jul 26 13:31:18 2017 +0200

    Gtk::Settings: Implement StyleProvider
    
    GtkSettings implements GtkStyleProvider.

 gtk/src/settings.hg |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/gtk/src/settings.hg b/gtk/src/settings.hg
index a9896b5..50b5e84 100644
--- a/gtk/src/settings.hg
+++ b/gtk/src/settings.hg
@@ -16,10 +16,10 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-
+#include <glibmm/object.h>
+#include <gtkmm/styleprovider.h>
 #include <gtkmm/toolbar.h>
 
-
 _DEFS(gtkmm,gtk)
 _PINCLUDE(glibmm/private/object_p.h)
 
@@ -29,9 +29,10 @@ namespace Gtk
 /** Sharing settings between applications.
  *
  */
-class Settings : public Glib::Object
+class Settings : public Glib::Object, public StyleProvider
 {
-   _CLASS_GOBJECT(Settings, GtkSettings, GTK_SETTINGS, Glib::Object, GObject)
+  _CLASS_GOBJECT(Settings, GtkSettings, GTK_SETTINGS, Glib::Object, GObject)
+  _IMPLEMENTS_INTERFACE(StyleProvider)
 protected: