How to fix the size of the view in Visualizer?

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

Hi, I am trying to visualize a sequence of point clouds with different boundingbox size. I set the Visualizer's parameters as followed:

```
vis = o3d.visualization.Visualizer()
vis.create_window(width=1024, height=768)
for i in range(N):
vis.add_geometry(point_cloud[i,...])
vis.get_view_control().convert_from_pinhole_camera_parameters(pose, allow_arbitrary=True)

ctr.set_front([-0.49286380699401849, -0.78134671467019068, -0.38286104428299134])
ctr.set_lookat([140.30607133474768, -94.898500645292486, -1235.2661697986696])
ctr.set_up([0.69253418495420604, -0.61865039974012825, 0.37103650166957053])
ctr.set_zoom(1.2400000000000004)
vis.poll_events()
vis.update_renderer()
vis.run()
vis.destroy_window()
```

The window's size is fixed. But the view's size seems to change over time since the boundingbox size of the point clouds changes, resulting in variational point cloud size of the same physical object. And the visulizaiton is shaking.
So how can I fix the view'size when visualizing different size of point clouds at different frames?