Good point Kevin - but many airliners have the cheat lines across the length of the windows, and these are provided as decals, so it could be done by masking the line of the decal, and applying the decal to bare plastic. I know it's fiddly, as I've done it, but worth it, as I think 'solid' windows, printed on the decals, spoil an otherwise good model, and more so on the flight deck windows. However, if the only decals available have windows printed on them, fair enough. But those flight deck windows could still be clear ....