procedure TForm1.FormCreate(Sender: TObject);
begin
  RegisterHotKey(Handle, IDHOT_SNAPDESKTOP, 0, VK_SNAPSHOT);
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  UnregisterHotKey(Handle, IDHOT_SNAPDESKTOP);
end;

procedure TForm1.FormActivate(Sender: TObject);
begin
 RegisterHotKey (Handle, IDHOT_SNAPWINDOW, MOD_ALT, VK_SNAPSHOT);
end;

procedure TForm1.FormDeactivate(Sender: TObject);
begin
  UnregisterHotKey(Handle, IDHOT_SNAPWINDOW);
end;