Как скрыть программу от Alt+Tab?

Вариант 1:

Source: Song

Source: https://forum.sources.ru

procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowWindow(Handle, SW_HIDE);
  ShowWindow(Application.Handle, SW_HIDE);
end;

Вариант 2:

Source: Stavros

Source: https://forum.sources.ru

with Application do
  begin
    ShowWindow(Handle, SW_HIDE);
    SetWindowLong(Handle, GWL_EXSTYLE, GetWindowLong(handle, GWL_EXSTYLE) or WS_EX_TOOLWINDOW);
  end; {With}
SetWindowLong(Handle, GWL_EXSTYLE, GetWindowLong(Handle, GWL_EXSTYLE) or WS_EX_TOOLWINDOW);