调用第三方程序，指定父窗体

[DllImport("user32.dll")]
        static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);

        [DllImport("user32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);

        private void button1_Click(object sender, EventArgs e)
        {
            System.Diagnostics.Process p = System.Diagnostics.Process.Start("calc");
            p.WaitForInputIdle();
            SetParent(p.MainWindowHandle, this.splitContainer1.Panel2.Handle);
            ShowWindowAsync(p.MainWindowHandle, 3);
        }