Changing the style of a scrollbar

[konton <konton gmail com>]

How do you change the look and size of a scroll bar?  I have a
GtkScrolledWindow that holds a GtkTreeView, and I want the scroll bars
to have different images and be thinner.  I tried setting the style in
.gtkrc for *GtkScrolledWindow* and I can get the color to change sort
of and even have somewhat of a background image overlayed on the
graphics, but it doesn't look like that's how I accomplish my task.

In the source code to GtkScrolledWindow I can see where it draws the
shadow around the contained widget, but not where it gets the up
arrow, down arrow, and slider images for the scroll bars.
gtkvscrollbar.c doesn't seem to have any graphics-related stuff in it.

This is not for a desktop application so I don't care about the user's
theme preference.

Thanks for any help,
Jason