Cross origin content and input

[RafaelCintron]

The spec has the following to say about cross origin content and input:

For a DOM overlay, XR input event data is treated as similar to mouse movement data. Poses remain available to the outer page if there is no cross-origin content, or if the cross-origin content is not receiving input, but are limited (blocked) when interacting with cross-origin content.

Does this mean the conforming UA must determine whether cross origin content is drawn anywhere inside of the DOM overlay element and, if so, stop returning all poses to the web developer? If so, that seems like a tough thing to determine for any random element. No?

In the context of VR DOM overlays, what does it mean for the cross-origin content to not receive input? Can the cross origin content only receive select-type input?

Can you please elaborate on the phase "but are limited (blocked) when interacting with cross-origin content"?