Function:   MNINFO( <expC1>,<expN1>,<expA1> )  --> string

Synopsis:   Displays a popup box with up to as many lines of a messages,
            that fit on the screen, NOT waiting for a Keypress.

            The amount that will fit on the screen will be calculated
            out of:
                      maximum number of displayable rows - 6

            The maximum width that will be displayed is:

                      maximum number of displayable columns - 6

            The message remains until removed with UNBOX()

            <expC1> message box color string; defaults to C_POPCOL

            <expN1> position of the box-shadow; defaults to C_SHADPOS

            <expA1> an array of messages

Examples:   MNMSG(,,{ "An error has been detected!" })
            MNMSG(,,{ "A","B","C","D","E","F" })

Notes:      The message is centered on screen in a box.

Returns:    underlying screen in string.
            Nothing on error.