Box Fill Color Mode for Rectangle

I've been enjoying using your shapes asset and even plan to make all my graphics out of them. One thing I noticed is that rect doesn't have a fill mode for box gradient, even though it has linear and radial gradient. Currently I need to use 4 triangles or polys in order to create a box gradient, as shown here. I do feel that it would be neat to have a box fill, with a value specifying thickness of the border.