def METHOD_NAME(self):
    """
    Paint the GL viewport
    """
    glViewport(*self.default_viewport())
    self.set_projection()
    glClearColor(*self.background_color)
    glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT )
    self.set_model_view()
    # self.test_paint()
    glEnable(GL_POLYGON_OFFSET_FILL)
    for item in self._items:
        glPolygonOffset(1.0, 10.0)
        item.render_solid()
        glPolygonOffset(0.0, 0.0)
        item.render_wireframe()
    glPolygonOffset(0.0, 0.0)