country borders on 2d-world

[Valerio S. <val...@gm...>]

Hello,
it is known that drawing a 2D map of the world is possible:
- http://www.gnuplotting.org/plotting-the-world-revisited/
- http://gnuplot.sourceforge.net/demo/world.html

But, suppose that I want to:
- also show the country/nation/state borders and
- some of the country/nation/states need to be highlighted somehow (a
different filling color than plain white would be ideal)

Ideally there would be several groups of country/nation/states sharing the
same filling colours

Has anyone ever attempted at this ?
Suggestions ?

Thanks,
--
Valerio