Distinguish labelled vs unlabelled BB/RECT based on color

[BinShet]

Is there any way to colour code the Rectangles to easily distinguish between labelled & unlabelled Bounding Boxes. Say, Initially the Box is red, but once I label it, it'll turn blue. I have a use case, where we'd be drawing multiple BB on render(upto 200), and then labelling them on by one. For cases wen the BBs are small, this could be useful.