Considering the above, do you still want me to write a patch for this?
Some options:
1. Add the above as a remark in the user guide or the wiki.
2. Add a variant of the dvipng backend, say dvipng-xcolor, as explained.
3. Remove the dvipng cli color code and (maybe just deprecate or ignore) the use-xcolor option altogether and make xcolor the default for every backend.
4. Do nothing.
What do you think?
Regards
--
Carlos