Sending keystroke/mouseclick via PostMessage() in C#

Question

I already got mouseclick to work with one issue. If I set delay between WM_MBUTTONDOWN and WM_MBUTTONUP to more than 5 ms it won't work. Why is that?

[DllImport("user32.dll")]
public static extern IntPtr 
PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

public void MouseClick(short x, short y)
        {
                IntPtr lParam = (IntPtr)((x & 0xFFFF) | ((y & 0xFFFF) << 16));
                const uint WM_MBUTTONDOWN = 0x0201;
                const uint WM_MBUTTONUP = 0x0202;

                PostMessage(hwnd, WM_MBUTTONDOWN, IntPtr.Zero, lParam);
                //System.Threading.Thread.Sleep(100);
                PostMessage(hwnd, WM_MBUTTONUP, IntPtr.Zero, lParam);
        }

Now, my goal is to send keystroke to minimized window (directx game). I tried using similar approach but nothing works. I bet that wParam is the problem.

        const uint WM_KEYDOWN = 0x100;
        const uint WM_KEYUP = 0x101;
        const uint WM_CHAR = 0x102;

        const int VK_W = 0x57;
        const int VK_S = 0x53;

        PostMessage(hwnd, WM_KEYDOWN, (IntPtr)VK_W, IntPtr.Zero);
        PostMessage(hwnd, WM_KEYUP, (IntPtr)VK_W, IntPtr.Zero);

How do I get this to work?

Remember that the window will be minimized so I can't use SendKeys or SendInput.

Answer 1

UPDATE:

This code works, but only for typing in in-game chat.

        const int VK_G = 0x47;

        const uint WM_KEYDOWN = 0x100;

        PostMessage(hwnd, WM_KEYDOWN, VK_G, 0);

I can't use it to walk forward etc.