gtkglextmm and libglademm warning at runtime

[Stathis Kamperis <ekamperi auth gr>]

Hello beautiful list :)

I have a problem combining gtkmm, gtkglextmm and libglademm.
Here is a code snippet:

class SimpleGLScene : public Gtk::DrawingArea,
                     public Gtk::GL::Widget<SimpleGLScene>
{
   // blabla
}

SimpleGLScene::SimpleGLScene(
                            BaseObjectType* cobject,
                            const Glib::RefPtr<Gnome::Glade::Xml>& 
refGlade) :
  Gtk::DrawingArea(cobject),
  Gtk::GL::Widget<SimpleGLScene>(static_cast<SimpleGLScene&>(*this)),
  m_refGlade(refGlade)
{
   // opengl init stuff here
}


At runtime, I get this:
(a.out:5236): GtkGLExt-CRITICAL **: gtk_widget_set_gl_capability: 
assertion `!GTK_WIDGET_REALIZED (widget)' failed

The weird thing is that when I remove Gtk::DrawingArea(cobject), the 
warning disappears.
I would highly appreciate any ideas.

Thank you all,
Stathis K
Greece