[GtkGLExt] Weird Bug with Gtk::GL::DrawingArea and Gtk::FileChooserDialog

[Sean Farrell <sean farrell baw de>]

Hello,
        
        first I want to apologize to send to two mailing lists,
        simultaneously,
        but I did not know who it concerned more. 
        
        I have a weird bug. I am using Gtk::GL::DrawingArea. I open a
        FileChooserDialog and suddenly I get the error message
        "GdkGLExt-WARNING
        **: glXMakeCurrent() failed" and in the next invocation of the
        exposure
        event a segmentation fault. It happens when the drawing area is
        redrawn
        in a exposure event. 
        
        I narrowed it down on the one side that only having the
        FileChooserDialog instantiated create the fault. 
        On the other side it happens in the line:
        
        Glib::RefPtr<Gdk::GL::Window> glwindow = this->get_gl_window();
        if (!glwindow->gl_begin(this->get_gl_context())) {
          return false;
        }
        
        I checked both Pointers they are valid; those returned by
        get_glwindow()
        and get_gl_context();
        
        What is odd, if I use other dialogs it dose not happen.
        
        Anyone a idea what I did wrong or how to work around the
        problem.
        
        Thank you in advance,
        
        Sean Farrell