Introduce GtkModelButton

Similar in spirit to GtkModelMenuItem, this private GtkButton subclass
can connect to a GtkMenuTrackerItem and present itself as either a
regular button, a check button, or a radio button. Activation and
state tracking is done through the GAction that is associated with
the menu tracker item.

https://bugzilla.gnome.org/show_bug.cgi?id=723014

gtk/gtkmodelbutton.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright © 2014 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the licence, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Matthias Clasen
+ */
+
+#ifndef __GTK_MODEL_BUTTON_H__
+#define __GTK_MODEL_BUTTON_H__
+
+#include <gtk/gtkwidget.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_MODEL_BUTTON                            (gtk_model_button_get_type ())
+#define GTK_MODEL_BUTTON(inst)                           (G_TYPE_CHECK_INSTANCE_CAST ((inst),                      \
+                                                             GTK_TYPE_MODEL_BUTTON, GtkModelButton))
+#define GTK_IS_MODEL_BUTTON(inst)                        (G_TYPE_CHECK_INSTANCE_TYPE ((inst),                      \
+                                                             GTK_TYPE_MODEL_BUTTON))
+
+typedef struct _GtkModelButton                            GtkModelButton;
+
+GType                   gtk_model_button_get_type                    (void) G_GNUC_CONST;
+
+GtkWidget *             gtk_model_button_new                         (void);
+
+G_END_DECLS
+
+#endif /* __GTK_MODEL_BUTTON_H__ */