anchor.diff:      FOnDropDown: TNotifyEvent;
       FOptions: TfpgComboOptions;
       FExtraHint: string;
  +    FReadOnly: Boolean;
       function    GetFontDesc: string;
       procedure   SetDropDownCount(const AValue: integer);
       procedure   SetFocusItem(const AValue: integer);
       procedure   SetFontDesc(const AValue: string);
       procedure   SetExtraHint(const AValue: string);
  +    procedure   SetReadOnly(const AValue: Boolean);
     protected
       FAutoSize: Boolean;
       FMargin: integer;
  
positive.code:   FocusItem = 0 it means the first item is selected etc. }
  procedure TfpgBaseComboBox.SetFocusItem(const AValue: integer);
  begin
    if FFocusItem = AValue then
      Exit; //==>
    FFocusItem := AValue;
  
negative.code:   if FExtraHint = AValue then
      Exit; //==>
    FExtraHint := AValue;
    Repaint;
  end;
  
  procedure TfpgBaseComboBox.SetReadOnly(const AValue: Boolean);
  begin
    if FReadOnly = AValue then exit;
    FReadOnly := AValue;
    Repaint;
  end;
  
  