frm.Show();Application.Run

static void Main()
         {/*
             Application.EnableVisualStyles();
             Application.SetCompatibleTextRenderingDefault(false);
             Application.Run(new Form1());
             */
             Form1 frm=new Form1();
             frm.Show();
             //frm.ShowDialog();
             Application.Run();
             
         }
        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
         {
             Environment.Exit(0);
         }