how to alter scrollbar thickness (width)?

["Rob Hodges" <s323140 student uq edu au>]

Hi,

I have a question that may be dreadfully simple but I can't find the
answer anywhere...

With Motif there is the magic incantation:

*XmScrollBar.width: 22

when placed in .Xdefaults all your Motif scrollbars become 22px wide.
Now, what is the equivalent incantation for a gtkrc?  Surely there is
one?  

I'm aware that some of the pixmap themes have wider scrollbars but I
don't have the horsepower to run those; I would just like to change
the width of the native scrollbar widgets.  Can anyone help?

Thanks,
-Rob