Background and foreground colour of disabled widgets

Background colour
 
In moving to the version 5.8.4 from 5.8.0 (I think), I have noticed that
the background colour of 'disabled' widgets is darker than it before.
 
Is there a widget option that sets this?  I have found in Learning
Perl/TK, page 72, the names of various colour options including
-disabledforeground but nothing about the background colour.  Is this
set when Perl is built or have I simply not looked in the right place?
 
Foregrpound colour
 
Also I tried to make all the text on disabled widgets black by using the
command line argument for the application (following Mastering Perl/Tk
page 410)
-xrm '*disabledforeground: black'
but nothing seemd to happen.  Should it have?
 
I am running the application under Windows XP
 
Best regards
 
Henry Merryweather