Alan, it seems that only NS uses 65280 as scale factor for 'color-values'; all other back-ends use 65535. Do you know if there is any reason for keeping it this way? Otherwise, I propose we change it (see patch).

It is probably just a relic from when colour components were scaled from 8 to 16 bits by multiplication with 256 instead of 257; this seems to have been fixed everywhere else.