Show solid view behind render region during viewport render

Sometimes, when rendering with small render regions, it can be easy to get lost in the viewport when trying to align the render region to a specific area in your scene. You either have to solid view or clear the render region, which is inconvenient. I propose that solid view should be shown behind the render region. If there are concerns about memory usage, perhaps there should be an option to turn it off in the Vieport Shading dropdown menu.

Current

Proposal