Transparency or specification of a second color for the spaces between the dashes/dots (for non-solid borders)

[hsendoukas]

When one tries to use a dashed or dotted border, the color used for the spaces between the dots/dashes is always white, which may be inappropriate in certain situations. Would it be possible to either let the caller specify a "fill-in" color or (better) avoid painting the "in-between" area (so that area is effectively transparent) ?

Thanks in advance for your consideration.