GTK_BUTTON & GTK_Style

["Simon Jerram" <simon jerram btinternet com>]

I'm having a problem with a button, (and indeed with getting
information)
it's fine except when disabled when the text is printed with a white
shadow 
which makes it look as if it may still be active.

What element of GtkStyle determines the shadow colour
of text in a GtkButton? 

Simple, polite question, hoping for a polite answer.