UNFREEZE_VP unfreezes a viewport.
---->(UNFREEZE_VP)----|viewport|---->
This action has no options.
Use this action when you want the graphics display of the
specified viewport to automatically update whenever a
modeling change occurs.
The viewport is redrawn as soon as it is unfrozen, so the
graphics display will be current.
Enter UNFREEZE_VP "vport1" to unfreeze the viewport
named "vport1".
LOCK_VP_DRAWLIST terminate action
FREEZE_VP terminate action