Failing to send key presses to a running process in C#

I'm using the following code to put the focus on a window (in this case, a notepad window), and sending some key presses to it everytime button 2 is clicked. However, when I press button 2, nothing happens. Can anyone tell my why my sendkeys command is failing?

public partial class Form1 : Form
{
    [DllImport("user32.dll")]
    static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

    private Process s;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        this.s = new Process();
        s.StartInfo.FileName = "notepad";
        s.Start();
        s.WaitF开发者_如何学编程orInputIdle();
    }

    private void button2_Click(object sender, EventArgs e)
    {
        ShowWindow(s.MainWindowHandle, 1);
        SendKeys.SendWait("Hello");
    }
}

ShowWindow is showing the started 'Notepad' but not giving it the input focus. Your sendkeys output is being received by form sending it, Form1.

Well, turns out this was the problem. I wasn't setting the focus to notepad correctly. The command SetForegroundWindow should have been used instead of ShowWindow.

 [DllImport("User32")]
    private static extern int SetForegroundWindow(IntPtr hwnd);

    private Process s;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        this.s = new Process();
        s.StartInfo.FileName = "notepad";
        s.Start();
        s.WaitForInputIdle();
    }

    private void button2_Click(object sender, EventArgs e)
    {
        //ShowWindow(s.MainWindowHandle, SW_RESTORE);
        SetForegroundWindow(s.MainWindowHandle);
        SendKeys.SendWait("Hello");
    }
}