A 3D spatial element representing a line of finite extent (line segment),
which is defined by a position point, a direction vector, and a length,
and by a head point and a tail point.
Sets the client data used by this data model for presentation, and
fires DataModel.clientDataChanged() events (whether or not the client
data has detectably changed).
Default implementation: Calls getGraphicTranslation(), computes
the relative offset, and adds the offset to the current graphic
position using graphic.getLocation() and graphic.setLocation().
Ignores no change in relationship, calls checkClearedRelationship()
after setting the relationship null, and checkSettingRelationship()
before setting it non-null.
If animation is enabled (see setAnimationSpeed()), shows the current
layout using realizeDisplay() and then sleeps for the frame time
multiplied by the animation speed factor.
A "simple" button trigger, which is stateless (can arm and fire
simultaneously), button level (not edge) sensing, and does not
perform trigger capture.
Syncs an aspect model event listener with the dynamic model state related
to all its registered child target models by sending appropriate "add"
and events.
Syncs a data model event listener with the dynamic model state related
to all its registered target models by sending appropriate "add" and
"changed" events.