winform如何防止多开

 
public Form2 myForm; 
if (myForm == null||myForm.IsDisposed)
                 {
                    myForm = new Form2();
                     myForm.Show();
                 }
                 else
                     {
                     myForm.Activate();
                     myForm.WindowState = FormWindowState.Normal;
                     }
                 }

[STAThread]
static void Main()
{
    bool onlyInstance = false;
    Mutex mutex = new Mutex(true, "UniqueApplicationName", out onlyInstance);
    if (!onlyInstance) {
        return;
    }
    Application.Run(new MainForm);
    GC.KeepAlive(mutex);
}