winform只能有一个实例运行且打开已运行窗口

static class Program 
{
    private static Mutex onlyOne;

    [STAThread]
    static void Main()
    {            
        onlyOne = new Mutex(true, Process.GetCurrentProcess().ProcessName);
        if (onlyOne.WaitOne(0, false))
        {
            Application.Run(new mainForm());
        }
        else
        {
            MessageBox.Show("应用程序已启动！"); ...