procedure TForm1.Button1Click(Sender: TObject);
var
  Rgn : hRgn;
begin
 {Hide the start button}
  Rgn := CreateRectRgn(0, 0, 0, 0);
  SetWindowRgn(FindWindowEx(FindWindow('Shell_TrayWnd', nil),
                                       0,
                                      'Button',
                                       nil),
                                       Rgn,
                                       true);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
 {Turn the start button back on}
  SetWindowRgn(FindWindowEx(FindWindow('Shell_TrayWnd', nil),
                                       0,
                                      'Button',
                                       nil),
                                       0,
                                       true);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
 {Disable the start button}
  EnableWindow(FindWindowEx(FindWindow('Shell_TrayWnd', nil),
                                       0,
                                       'Button',
                                       nil),
                                       false);
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
 {Enable the start button}
  EnableWindow(FindWindowEx(FindWindow('Shell_TrayWnd', nil),
                                       0,
                                       'Button',
                                       nil),
                                       true);
end