High-contrast colours

[Callum McKenzie <callum physics otago ac nz>]

The recent thread on gok and a bug report for gnomine (112571) have
made me realise that there might be a need for GtkStyle to also
supply a list of "high-contrast" colours that an application might
need (just as it supplies a light colour and a dark colour that
matches the theme).

In the case of gnomine there is a need for eight visually distinctive
colours that don't fade into the background. You don't actually need
the colours, but most people who have played it will probably agree
that they are helpful. Currently these colours are hard-coded and
it is quite easy to find a theme which will make one or more of them
difficult to see (this is what the bug report is about).

Of course there are reasons for not doing this:
 - The Gtk theme creators will throw fits about having to come up with
   eight colours that contrast with each other and their chosen
   background (especially if it's a pixmap background).
 - Given these high-contrast colours people will use them
   indiscriminantly. The results will be hideous.
 - Old themes will not have this information and whatever defaults are
   used for the high-contrast colours will send us back to square one.
 - It adds even more crap to the API (although it shouldn't break anything).

What are peoples thoughts about this ?

 - Callum

PS: I know this is technically a GTK issue, but the people here are
the people who might actually use it. Best to check that someone
actually wants it in the first place right ?