The Change the Viewport Associated with a Virtual Display routine
    changes the size of an existing viewport in a virtual display.
    The text currently in the viewport is remapped to fit the new
    dimensions.

    Format

      SMG$CHANGE_VIEWPORT  display-id [,viewport-row-start]

                           [,viewport-column-start]

                           [,viewport-number-rows]

                           [,viewport-number-columns]

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

2  –  Arguments

 display-id

    OpenVMS usage:identifier
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference

    Identifier of the virtual display containing the viewport to be
    changed. The display-id argument is the address of an unsigned
    longword containing this identifier.

 viewport-row-start

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    Optional row number in the virtual display that will become row
    1 in the changed viewport. The viewport-row-start argument is
    the address of a signed longword containing the row number. If
    omitted, the present viewport-row-start value is used.

 viewport-column-start

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    Optional column number in the virtual display that will become
    column 1 in the changed viewport. The viewport-column-start
    argument is the address of a signed longword containing the
    column number. If omitted, the present viewport-column-start
    value is used.

 viewport-number-rows

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    Optional number of rows in the changed viewport. The viewport-
    number-rows argument is the address of a signed longword
    containing the number of rows. If omitted, the present viewport-
    number-rows value is used.

 viewport-number-columns

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    Optional number of columns in the changed viewport. The viewport-
    number-columns argument is the address of a signed longword
    containing the number of columns. If omitted, the present
    viewport-number-columns value is used.