XTREE refinement: all other exitcodes now take precedence over -48 (validation). So for example, if the user edits a cell, then clicks on the "X" button to close the dialog before otherwise exiting from the cell editing operation, the ESCAPE exitcode (1) will be returned in the exitcode parameter, and -48 will be added to the xinfo parameter. Applications should rely on the XTR.XVALIDATE field in the xtrctl parameter to determine whether validation is needed, and on the exitcode parameter to determine what the user has requested to do next. Note that this has been the existing behavior all along for most exitcodes; this change mainly extends it to the special case of a button sending ESCAPE.
