static class Program {
[STAThread]
static void Main() {
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
var start = new Form1();
start.FormClosed += WindowClosed;
start.Show();
Application.Run();
}
static void WindowClosed(object sender, FormClosedEventArgs e) {
if (Application.OpenForms.Count == 0) Application.Exit();
else Application.OpenForms[0].FormClosed += WindowClosed;
}
}