if (wc == null)
wc = (WorkingCalendar) getProject().getWorkCalendar();
CalendarService service = CalendarService.getInstance();
ChangeWorkingTimeDialogBox dlg = ChangeWorkingTimeDialogBox
.getInstance(getGraphicManager().getFrame(), project,wc, documentCalendars,restrict,this.getUndoController());
dlg.doModal();
}