Define the scroll types.
This class allows you to create your own scroll types. By default,
two types are defined : VERTICAL and HORIZONTAL. Note that
if you want to create your own scroll types, there must be a correlation
between the two properties (_x/_width or _y/_height).
static public VERTICAL:ScrollType [Read Only]This type uses _y as scroll property and
_height as size property.
static public HORIZONTAL:ScrollType [Read Only]This type uses _x as scroll property and
_width as size property.