Adding theme support to programs

[Dave <dms22 cam ac uk>]

Hi all,

Apologies if this is a stupid question, but I can't find *any*
documentation for it anywhere, or even nice simple programs to pull apart
and analyse. So...

How do you make a Gtk program theme-aware? I don't want to have to resort
to GNOME unless it's really necessary. The tutorials for GNOME don't even
mention themes, and the reference section of www.gtk.org doesn't tell you
how to *use* any of the theming commands. I have no idea what the program
is expected to do (lots or very little) for its widgets to have the user
specified theme in it.

Thanks for any advice,

-Dave