graphics.h:

class Graphics
{
        private:
                GtkWidget *worldView;
                GdkPixmap *worldViewPixMap;

                static gboolean worldViewExpose( GtkWidget      *widget,
                              GdkEventExpose *event );
};



----------------------

graphics.c:

gboolean Graphics::worldViewExpose( GtkWidget      *widget,
                              GdkEventExpose *event )
{
  gdk_draw_drawable (widget->window,
                     widget->style->fg_gc[GTK_WIDGET_STATE (widget)],
                     (Graphics::worldViewPixMap),
                     event->area.x, event->area.y,
                     event->area.x, event->area.y,
                     event->area.width, event->area.height);

  return FALSE;
}


in Graphics::Graphics():

        g_signal_connect (G_OBJECT (worldView), "worldViewExpose", G_CALLBACK (&Graphics::worldViewExpose), NULL);


error:
graphics.h: In static member function ‘static gboolean Graphics::worldViewExpose(GtkWidget*, GdkEventExpose*)’:graphics.h:29: error: invalid use of member ‘Graphics::worldViewPixMap’ in static member function
graphics.c:16: error: from this location [which is (Graphics::worldViewPixMap)]