\section{Scrollbar.mui}

The Scrollbar class has no objects and attributes itself.
It just connects a proportional gadget and two button
gadgets with approriate imagery to make up a scrollbar.

Since Scrollbar class is a subclass of Group class,
every attribute and method is passed through to all
of its children. Thus, you can talk and listen to
a scrollbar as if it was just a single prop gadget.

You can use the attribute MUIA\_Group\_Horiz as with
any other group to determine if the scrollbar should
be horizontal or vertical. By default, a vertical
scrollbar is generated.