[Feature Request] Option to customize or disable the "picking sphere" visual in VisualizerWithEditing

[FOOLwrc]

Checklist

• I have searched for similar issues.
• For Python issues, I have tested with the latest development wheel.
• I have checked the release documentation and the latest documentation (for main branch).

Proposed new feature or change

Is your feature request related to a problem? Please describe.
I am using o3d.visualization.VisualizerWithEditing for a point cloud interaction tool. When I use Shift + Left Click to pick a point, Open3D automatically renders a large golden/yellow sphere at the picked location.

This sphere is too large relative to my point cloud details and obstructs the view. I tried to disable it by setting opt.show_coordinate_frame = False, but the sphere persists.

Describe the solution you'd like
I would like an option to:

1. Completely disable the visual feedback (the golden sphere) during point picking.
2. Or allow customization of the sphere's radius/color via the API.

Describe alternatives you've considered
Currently, I have to scale my entire point cloud up (Gulliver Transformation) to make the fixed-size sphere appear relatively smaller, which is not an ideal workflow.

Additional context

• Open3D Version: 0.19.0
• OS: Windows 10
• Code snippet:

# Even with show_coordinate_frame=False, the sphere appears on click
vis = o3d.visualization.VisualizerWithEditing()
vis.create_window()
opt = vis.get_render_option()
opt.show_coordinate_frame = False 
vis.run()

<img width="1200" height="800" alt="Image" src="https://github.com/user-attachments/assets/abeb034f-eb3a-467a-b671-fc1c8b52db7a" />

<img width="898" height="493" alt="Image" src="https://github.com/user-attachments/assets/a0e8a4fa-8ada-4c94-a315-1f87b35f1ee2" />

### References

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### Additional information

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