[XeTeX] colour \specials not working with xdvipdfmx driver?

[Paul Howson]

Another fault has arisen with xetex on linux (Red Hat).

These two \special commands colourise rules or type:

\special{x:rulecolor=<hex rgb value>}
\special{x:textcolor=<hex rgb value>}

where <hex rgb value> is a 6 digit hex color value.

They work fine with xetex on the Mac.

On linux, with the xdvipdfmx driver, no errors are reported, but the  
commands have no effect -- i.e. subsequent rules or text are not  
coloured.

Test files are:
FILE 1: (should put a red rule under a line of type)

	the quick brown fox\par
	\special{x:rulecolor=ff0000}
	\hrule height 10pt

FILE 2: (should make red type)

	\special{x:textcolor=ff0000}
	the quick brown fox\par

As reported both work fine on MacOS, but produce black-only rules and  
text on linux with the xdvipdfmx driver.

Any help would be appreciated.

Thanks,
Paul Howson