function TCustomStatusBar.ExecuteAction(Action: TBasicAction): Boolean;
begin
  if AutoHint and (Action is THintAction) and not DoHint then
  begin
    if SimplePanel or (Panels.Count = 0) then
      SimpleText := THintAction(Action).Hint else
      Panels[0].Text := THintAction(Action).Hint;
    Result := True;
  end
  else Result := inherited ExecuteAction(Action);
end;

在MDI中谁来CALL?

bool TCustomStatusBar::ExecuteAction(TBasicAciton& Action)
{
    if(AutoHint && Action.IsKindOf(THintAction) && !DoHint())
       if (SimplePanel || Panels.Count == 0)
           SimpleText = Action.Hint ;
       else
           Panels[0].Text = Action.Hint;
       return true;
    return Base::(?)ExecuteAction(Action);    

}