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:   FDropDownCount  := 8;
    FMargin         := 1;
    FFocusItem      := -1; // nothing is selected
    FItems := TStringList.Create;
    FItems.OnChange := @InternalItemsChanged;
    FFont := fpgGetFont('#List');
  
negative.code:   Canvas.SetClipRect(r);
  
    if Enabled then
    begin
      if ReadOnly then
        Canvas.SetColor(clWindowBackground)
      else
        Canvas.SetColor(FBackgroundColor);
    end
    else
      Canvas.SetColor(clWindowBackground);
  
  