twSetStruct( wT, wL, wB, wR, sT, sL, sB, sR, uScr )
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     Replace the current window structure. This function must be used
     with extreme care as you really mess things up with it. It is an
     internal TSDWIN function but available for those who wish to
     develop their own functions.

     twMove() and twSlide() use this function.

       Arguments:

     wT,wL,wB,wR - 'N' New Window Coordinates.

     sT,sL,sB,sR - 'N' Saved screen coordinates.

     uScr        - 'C' Screen with which to replace the current HIDDEN
                       screen.

       Return:

     .T.

       Example:

     twSetStruct( 3, 3, 10, 60, 3, 3, 11, 62, SAVESCREEN( 3, 3, 11, 62 ))