How SceneWidget picks points

I want to use Open3D’s GUI module to create a small application with the ability to select points and get them, but I’m having some problems:

  • Could someone tell me how gui.scenewidget picks points and gets them?

  • I loaded an OBJ model with gui.scenewidget and set it to Controls.PICK_POINTS, but it didn’t have any effect. Also, gui.SceneWidget does not have a method to get the selected index.

self._scene = gui.SceneWidget()
self._scene.scene = rendering.Open3DScene(w.renderer)