NAME
       GetCode -- return the true IDCMP message code
   SYNOPSIS
       code = GetCode( imsg )
       UWORD GetCode( struct IntuiMessage * )
   FUNCTION
       Returns the true IntuiMessage code field. Layout.gadget replaces
       the IDCMP_GADGETUP message with an IDCMP_IDCMPUPDATE. This function
       will return the "gadgetup code" from the IDCMPUPDATE taglist if it
       is found there, and otherwise the normal imsg->Code.
   INPUTS
       imsg -- a pointer to an IntuiMessage
   RESULTS
       The message's code field