Отправка сообщений в окно

//**********WinAPI функции*********
 
    [DllImport("user32.dll", EntryPoint = "FindWindow")] 
    private static extern IntPtr FindWindow(string _ClassName, string _WindowName); 
 
    [DllImport("user32.dll", EntryPoint = "FindWindowEx")] 
    private static extern IntPtr FindWindowEx(IntPtr hwndPrnt, IntPtr hwndChildAfter, string _ClassName, string _WindowName); 
 
    [DllImport("user32.dll", CharSet = CharSet.Auto)] 
    public static extern int SendMessage(IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam);
 
    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    public static extern int MessageBox(IntPtr hWnd, String text, String caption, uint type);
 
    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    public static extern int DestroyWindow(IntPtr hWnd);
 
    
 
//*********/WinAPI функции*********
 
 
//**********WinAPI константы*********
    const int BM_SETSTATE = 243; 
    const int WM_LBUTTONDOWN = 513; 
    const int WM_LBUTTONUP = 514; 
    const int WM_KEYDOWN = 256; 
    const int WM_CHAR = 258; 
    const int WM_KEYUP = 257; 
    const int WM_SETFOCUS = 7; 
    const int WM_SYSCOMMAND = 274; 
    const int SC_MINIMIZE = 32;
    const int WM_CLOSE = 0x0010;
    const int VK_F1 = 0x70;   //F1 key 
    const int VK_F2 = 0x71;   //F2 key 
    const int VK_F3 = 0x72;   //F3 key 
    const int VK_F4 = 0x73;   //F4 key 
    const int VK_F5 = 0x74;   //F5 key 
    const int VK_F6 = 0x75;   //F6 key 
    const int VK_F7 = 0x76;   //F7 key 
    const int VK_F8 = 0x77;   //F8 key 
    const int VK_F9 = 0x78;   //F9 key 
    const int VK_F10 = 0x79;   //F10 key 
    const int VK_F11 = 0x7A;   //F11 key 
    const int VK_F12 = 0x7B;   //F12 key
    const int VK_0 = 0x30;   //0 key 
    const int VK_1 = 0x31;   //1 key 
    const int VK_2 = 0x32;   //2 key 
    const int VK_3 = 0x33;   //3 key 
    const int VK_4 = 0x34;   //4 key 
    const int VK_5 = 0x35;   //5 key 
    const int VK_6 = 0x36;    //6 key 
    const int VK_7 = 0x37;    //7 key 
    const int VK_8 = 0x38;   //8 key 
    const int VK_9 = 0x39;    //9 key
 
 
//*********/WinAPI константы*********
 
 
 
private void button1_Click(object sender, EventArgs e)
{
    IntPtr hWnd = FindWindow(null, comboBox1.SelectedItem.ToString()); 
    IntPtr t1;
    if (hWnd == IntPtr.Zero) 
    { 
        MessageBox(new IntPtr(0), "Not found main", "Error", 0);
        return; 
    }
    IntPtr hEdit = FindWindowEx(hWnd, IntPtr.Zero, "Button", "5");
    if (hEdit == IntPtr.Zero)
    {
        MessageBox(new IntPtr(0), "Not found child", "Error", 0);
        return;
    } 
   
        t1 = (IntPtr)116;
     // Scan-код символа "9" (F1 = 112, F2 = 113, F3 = 114 ... F10 = 121)
    IntPtr nul = IntPtr.Zero; 
    int retValue;
 
    retValue = SendMessage(hEdit, WM_SETFOCUS, nul, nul);
    retValue = SendMessage(hEdit, WM_KEYDOWN, t1, nul);
    //retValue = SendMessage(hEdit, WM_CHAR, t1, nul);
    retValue = SendMessage(hEdit, WM_KEYUP, t1, nul);
}

keybd_event(VK_F1, 0, 0, 0);