[glibmm] Added a TODO

[Murray Cumming <murrayc src gnome org>]

commit f23ef4d2335fdabab739672c0bf9af8b26370738
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Dec 22 23:23:25 2010 +0100

    Added a TODO

 glib/glibmm/refptr.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/glib/glibmm/refptr.h b/glib/glibmm/refptr.h
index f6312f0..e57cf1c 100644
--- a/glib/glibmm/refptr.h
+++ b/glib/glibmm/refptr.h
@@ -155,6 +155,9 @@ public:
   template <class T_CastFrom>
   static inline RefPtr<T_CppObject> cast_const(const RefPtr<T_CastFrom>& src);
 
+  //TODO: Remove these if we replace operator bool() with operator void* after 
+  //an API/ABI break, as suggested by Daniel Elstner? murrayc.
+
   /** Compare based on the underlying instance address.
    *
    * This is needed in code that requires an ordering on