A TextLayoutEvent instance represents an event, such as the
TextLayoutEvent.SCROLL event, that does not require
A scroll event is represented by a TextLayoutEvent instance with its
type property set to TextLayoutEvent.SCROLL.
A class specifically for scroll events is not necessary because there are
no custom properties for a scroll event, as there are for the other
events that have specific event classes.
If a new text layout event is needed, and the event does not require
custom properties, the new event will also be represented by a
TextLayoutEvent object, but with its type property
set to a new static constant.