Overlay viewports do not block picking world coordinate projection

Target Use case

My use case involves a view for static overlay/interface, and another view for dynamic panning/zooming. Both the overlay view and the dynamic view fill the screen, with the overlay view being on top. The overlay view has controller: false and all contained layers with pickable: false. I am also using event callbacks.

On hover, etc, unless a layer from the dynamic view gets picked, picking will use the static overlay viewport - this means that the generated world coordinate values are projected from the static viewport, instead of the below dynamic viewport, despite having no pickable layers or controller.

Proposed feature

Prevent 'overlay' viewports from being selected when picking.

This feature could possibly (?) be implemented in several ways:

1. A boolean prop for overlay views (overlay: true) preventing viewport use in picking
2. Views with controller: false not used for picking

To Do List

• Add label and assign to milestone
• Coding
• Doc update
• What’s new update
• Test

Start by tracing deck.gl's picking flow and how it selects the overlay and dynamic viewports; the issue does not name specific files or tests. Compare the proposed overlay and controller-based approaches, then verify that a non-pickable overlay cannot provide the world-coordinate projection while the underlying dynamic viewport still can. Add coverage and documentation for the chosen behavior.