What gets changed when unfocusing the Unity Editor?

When I unfocus the Unity Editor(dual screen setup), a water shader fails/stops working (using the forward renderer), the uv distortion is suddenly gone on the reflective top surface of the water. The exact same disappearing uv distortion on a reflective surface also happens if I switch the renderer to the 2d renderer. Is there any list of things that change when unfocusing the Unity Editor and is there any list of technical changes between the forward and 2d renderer? (perhaps a different approach of the camera depth texture?) The fact of the matter is, I need to get this distrotion on the reflective surface working for the 2d renderer.