Procedure EditString(X,Y:Word;MaxLets:Byte;
                         Upper:Boolean;Var MainStr:String)

    Note

    Save  the  background  (by  opening  a  window)  before  calling this
    procedure.

    A string MainStr  is  edited  at  X,Y.   The  string  is  limited  to
    MaxLets characters  and  if  Upper  is  True  the  string is returned
    in capital letters.