def on_add_face_clicked(self, a) :
e = sr_py.CommandEvent("OpenGLViewer")
e.set_command("add face")
sr_py.add_command_event(e)
def on_rm_faces_clicked(self, a) :
e = sr_py.CommandEvent("OpenGLViewer")
e.set_command("delete faces")
sr_py.add_command_event(e)
