The Create a Virtual Viewport routine creates a viewport and
    associates it with a virtual display. The location and size of
    the viewport are specified by the caller.

    Format

      SMG$CREATE_VIEWPORT  display-id ,viewport-row-start

                           ,viewport-column-start

                           ,viewport-number-rows

                           ,viewport-number-columns

  Additional Information (explode) :

• Returns
• Arguments