Overlay should also affect background prototype

Hello,
Today, if you can have an overlay on a prototype which adds a background color between the “source” and the overlay. This background is applied in the whole prototype: but if the prototype is not matching the screen size, it is not applied to the prototype background color. This makes the prototypes sometimes look weird. It would be good if the overlay background color would “spill over” to the default prototype background color as well.