twAddMSpot( aMouseSpot, nNxtHandl, aDef, nHandle )
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     Add a mouse Hot Spot to an array of hot spots held in the caller.
     TSDWIN mouse supported functions all have auxiliary functions
     which simplify this call for you.

       Arguments:

     aMouseSpot - 'A' An array in the caller in which to store the hot
                      spot being defined.

     nNxtHandl  - 'N' The next free spot in the array. This parameter
                      must be called by reference.

     aDef       - 'A' An array defining the hot spot. It should at the
                      very minimum contain the coordinates of the spot
                      and a code block to execute. See, for example,
                      twRAHotSpot() to see how this function is called
                      by TSDWIN functions.

     nHandle    - 'N'

       Return:

     The handle of the hot spot so that it MAY BE  RELEASED later.

       Example:

     This function creates a hot spot. The function is defined in the
     calling program file which also contains a file-wide STATIC called
     'aMouseSpot' to hold the hot spot information. When you use this
     method, be sure to restore the static to {} when exiting.

        FUNCTION HotSpot( nRowTop, nColLeft, nRowBot, ;
                          nColRight, bAction, nButton,;
                          nPause, lRelease )
        RETURN twAddMSpot( aMouseSpot, @nNxtHandl,;
                {nRowTop, nColLeft, nRowBot, nColRight, bAction,;
                IIF( nPause = NIL, twSetMPause(), nPause ),;
                IIF( lRelease = NIL, twSetMRTime(), lRelease ),;
                IIF( nButton = NIL, 0, nButton ), .T.