unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    ShowButton: TButton;
    HideButton: TButton;
    procedure ShowButtonClick(Sender: TObject);
    procedure HideButtonClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.ShowButtonClick(Sender: TObject);
var
  wndHandle : THandle;
  wndClass : array[0..50] of Char;
begin
  StrPCopy(@wndClass[0], 'Shell_TrayWnd');
  wndHandle := FindWindow(@wndClass[0], nil);
  ShowWindow(wndHandle, SW_RESTORE);
end;

procedure TForm1.HideButtonClick(Sender: TObject);
var
  wndHandle : THandle;
  wndClass : array[0..50] of Char;
begin
  StrPCopy(@wndClass[0], 'Shell_TrayWnd');
  wndHandle := FindWindow(@wndClass[0], nil);
  ShowWindow(wndHandle, SW_HIDE);
end;

end.