Is there any *user* documentation for gtkrc files?

[Guy Harris <gharris flashcom net>]

Somebody asked on the Ethereal developer's mailing list how to make
Ethereal's packet-data pane (a GtkText window) not choose a dark
background (which didn't contrast well with the black text); I suggested
that his system's global "gtkrc" file, or his personal "gtkrc" file,
might have chosen a dark background for them, and suggested that he
might check that and tweak one of those files, but the only
documentation I know of for the "gtkrc" file is the "GTK's rc Files"
section of the GTK 1.2 tutorial.

Is there some better document to which I could have referred him?