UNLOCK_VP_DRAWLIST unlocks the drawlist of the specified
viewport.
---->(UNLOCK_VP_DRAWLIST)----|viewport|---->
This action has no options. The drawlist of the specified
viewport is unlocked.
Use this action to unlock the drawlist of a specified
viewport. After the drawlist has been unlocked, workplanes
and parts that are created will be displayed in the viewport.
Enter UNLOCK_VP_DRAWLIST "vport1" to unlock the drawlist
of the viewport named "vport1".
LOCK_VP_DRAWLIST terminate action