unit Unit1; {$mode objfpc}{$H+} interface uses Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, ComCtrls; type { TForm1 } TForm1 = class(TForm) Button1: TButton; CheckBox1: TCheckBox; Label1: TLabel; Label2: TLabel; TrackBar1: TTrackBar; procedure Button1Click(Sender: TObject); private public end; var Form1: TForm1; implementation {$R *.lfm} { TForm1 } procedure TForm1.Button1Click(Sender: TObject); begin Button1.Caption:='Hello'; end; end.