Ubuntu 9.04 (and other distros) still are shipping libcroco-0.6.1. (0.6.2 was released in February and is in Fedora 11.)

With libcroco-0.6.1 the calendar and LookingGlass are reported to have completely transparent backgrounds. I think this is because of:

  https://bugzilla.gnome.org/show_bug.cgi?id=394680

Which was fixed in January 2007 but not in a release until 0.6.2. A bit hard to deal with because the misparsing gets done at the tokenization step before we get involved.

One idea about this is to introduce parsing for the (non-CSS-standard) notation:

 #rrggbbaa #rgba

and use that instead of rgba(r,g,b,percentage)

until we don't have to worry about libcroco any more. I think this is possible, though not completely sure - if it's possible the way it would work is that before st-theme-node.c:get_color_from_term() calls cr_rgb_set_from_term(), it needs to do something like:

  else if (term->type == TERM_HASH)
    {
      return get_color_from_hex (term, color);
    }

but it's possible that at the parse step libcroco has already converted TERM_HASH to TERM_RGB. 

The other idea I have is to use cr_om_parser_simply_parse_buf() instead of cr_om_parser_simply_parse_file() and do a search-and-replace on our CSS files when loading them and replace rgba with _rgba and handle that in addition to rgba(). This probably would be conditionalized on 

#if LIBCROCO_VERSION_NUMBER < 602