[gtkmm] Gtk::Object: Add dont_allow_use_in_glib_refptr_ .

[Murray Cumming <murrayc src gnome org>]

commit ae7bf5bb51423c2c1e16397da7e00c4e6c17f34b
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Sep 16 10:35:36 2015 +0200

    Gtk::Object: Add dont_allow_use_in_glib_refptr_ .
    
    To deprecate the use of RefPtr with widgets and other Gtk::Object-derived
    classes. We could just prevent this regardless of deprecation, but
    deprecating it seems kinder in case someone has managed to do it so far.
    Bug #755048

 gtk/gtkmm/object.h |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkmm/object.h b/gtk/gtkmm/object.h
index 044c4a5..8d20b3c 100644
--- a/gtk/gtkmm/object.h
+++ b/gtk/gtkmm/object.h
@@ -63,6 +63,14 @@ class GTKMM_API Object : public Glib::Object
   typedef GObjectClass BaseClassType;
 #endif /* DOXYGEN_SHOULD_SKIP_THIS */
 
+#ifdef GTKMM_DISABLE_DEPRECATED
+  /** This prevents use of Gtk::Object-derived classes with RefPtr.
+   * RefPtr should only be used with classes that have create() methods
+   * that return RefPtr.
+   */
+  typedef int dont_allow_use_in_glib_refptr_;
+#endif
+
   Object(Object&& src) noexcept;
   Object& operator=(Object&& src) noexcept;