[gtkmm/sigc3v2: 2/4] GtkMainConnectionNode: Derived from sigc::notifiable.

[Murray Cumming <murrayc src gnome org>]

commit 28cc0c990d94e85753ea782da31ffba574800693
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Mar 8 13:40:09 2016 +0100

    GtkMainConnectionNode: Derived from sigc::notifiable.

 gtk/src/main.ccg |   12 +++++-------
 1 files changed, 5 insertions(+), 7 deletions(-)
---
diff --git a/gtk/src/main.ccg b/gtk/src/main.ccg
index 5b266a5..ba099b3 100644
--- a/gtk/src/main.ccg
+++ b/gtk/src/main.ccg
@@ -39,7 +39,7 @@ namespace
  * be handled by a single class.  Special handling is needed for signals that
  * don't support destroy notification; see the comment on connection_list_.
  */
-class GtkMainConnectionNode
+class GtkMainConnectionNode : public sigc::notifiable
 {
 public:
   // A function taking a connection id, e.g. gtk_timeout_remove().
@@ -47,8 +47,8 @@ public:
 
   explicit GtkMainConnectionNode(const sigc::slot_base& slot);
 
-  static void* notify(void* data);
-  static void destroy_notify_handler(void* data);
+  static void notify(sigc::notifiable* data);
+  static void destroy_notify_handler(sigc::notifiable* data);
 
   // Call this after installing the GTK+ callback.
   void install(guint conn_id, RemoveFunc remove_func, bool has_destroy_notify);
@@ -93,7 +93,7 @@ GtkMainConnectionNode::GtkMainConnectionNode(const sigc::slot_base& slot)
 }
 
 //static:
-void* GtkMainConnectionNode::notify(void* data)
+void GtkMainConnectionNode::notify(sigc::notifiable* data)
 {
   // notification from the sigc++ side ...
 
@@ -116,12 +116,10 @@ void* GtkMainConnectionNode::notify(void* data)
     // destruction of slot_ notifies all objects referring to it.
     delete self;
   }
-
-  return nullptr;
 }
 
 // static
-void GtkMainConnectionNode::destroy_notify_handler(void* data)
+void GtkMainConnectionNode::destroy_notify_handler(sigc::notifiable* data)
 {
   // notification from the gtk+ side ...