[glibmm] Glib::ExtraClassInit docs: Don't mention Gtk::WidgetCustomDraw

[Kjell Ahlstedt <kjellahl src gnome org>]

commit f9e1864b2d407b4aff7b009ccaa6b8671b5cbb3c
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Thu May 24 11:18:01 2018 +0200

    Glib::ExtraClassInit docs: Don't mention Gtk::WidgetCustomDraw
    
    Gtk::WidgetCustomDraw has been removed. Don't mention it in the
    class documentation of Glib::ExtraClassInit.

 glib/glibmm/extraclassinit.h | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)
---
diff --git a/glib/glibmm/extraclassinit.h b/glib/glibmm/extraclassinit.h
index 9af64d2d..22a0e822 100644
--- a/glib/glibmm/extraclassinit.h
+++ b/glib/glibmm/extraclassinit.h
@@ -47,20 +47,19 @@ namespace Glib
  *   }
  *   static void my_instance_init_function(GTypeInstance* instance, void* g_class)
  *   {
- *     gtk_widget_set_has_window(GTK_WIDGET(instance), true);
+ *     gtk_widget_set_has_surface(GTK_WIDGET(instance), true);
  *   }
  *
  *   Glib::ustring m_css_name;
  * };
  *
- * class MyWidget : public Gtk::WidgetCustomDraw, public MyExtraInit, public Gtk::Widget
+ * class MyWidget : public MyExtraInit, public Gtk::Widget
  * {
  * public:
  *   MyWidget()
  *   :
  *   // The GType name will be gtkmm__CustomObject_MyMidget
  *   Glib::ObjectBase("MyWidget"), // Unique class name
- *   Gtk::WidgetCustomDraw(),
  *   MyExtraInit("my-widget"),
  *   Gtk::Widget()
  *   {
@@ -70,8 +69,8 @@ namespace Glib
  * };
  * @endcode
  *
- * @note Classes derived from %ExtraClassInit (Gtk::WidgetCustomDraw and MyExtraInit
- * in the example) must be listed before Glib::Object or a class derived from
+ * @note Classes derived from %ExtraClassInit (MyExtraInit in the example)
+ * must be listed before Glib::Object or a class derived from
  * %Glib::Object (Gtk::Widget in the example) in the list of base classes.
  *
  * @newin{2,58}