twKeyStack( aKeys )
 ----------------------------------------------------------------------------
     Save an array of SETKEY assignments to an internal TSDWIN stack
     for later retrieval.

       Arguments:

     aKeys - 'A' An array of key codes for  which information is to be
                 saved. aKeys defaults to the first TEN function keys.

       Return:

     Numeric handle indicating the position in the internal stack in
     which the information is saved.

       Example:

     nKHandle := twKeyStack( { K_F1, K_F2, K_F9 } )