Question about compose a picasa style scrollbar, about the GtkVScale UI drawing

["MD Tsai" <md tsai gmail com>]

Hi all,

I don't know if this is the correct mailing list to post my question, and
sorry for my poor English.

I'm trying to write a "picasa style"-like scrollbar. That is, there is a
slider which is always in the center of the scrollbar, and there is a shadow
indicates the current page position and size of total pages. So the shadow
is like the original gtk scrollbar but it is not scrollable by dragging the
shadow, only pressing the up/down arrows can control the page position. The
center slider is scrollable, when it is dragged far from center, the page
scrolls fast. When mouse release, the slider returns to the center of the
scrollbar.

In this concept, I write a composed gtk widget, use GtkVScale and
GtkVScrollbar. GtkVScale is the slider and the GtkVScrollbar is the shadow
part. The actions is simple, I just let the GtkVScale's adjustment always
set it's value to have of upper value when mouse button release. But the UI
presentation is a problem, the GtkVScale has a gutter and will be filled
with some colors according to different theme engine. So I can't see the
GtkVScrollbar's status. I'm wondering to know how to let the gutter of
GtkVScale be invisible. What is help? RC file? Write another new theme
engine or others? I've no idea about the rendering model of gtk. So I can't
choose the correct solution. Please kindly give me some hint to write this
widget.

Kindly regards,

Eric Tsai