Click inside DirectX game while window is in background without bringing it to foreground

i'm currently trying to send input ( mouse currently, keyboard soon :D ) inside a DirectX game but i have no success. From my current tests, i've only managed to get it clicked if the window is in front. Here is the code ...

using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Threading;
using System.Windows.Forms;

namespace hots
{
    public static class Mouse
    {
        [DllImport("user32.dll")]
        private static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

        //[DllImport("user32.dll", CharSet = CharSet.Auto)]
        //private static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lparam);

        // The SendMessage function sends the specified message to a window or windows. 
        // It calls the window procedure for the specified window and does not return
        // until the window procedure has processed the message. 
        [DllImport("User32.dll")]
        public static extern Int32 SendMessage(
            IntPtr hWnd,               // handle to destination window
            int Msg,                // message
            IntPtr wParam,             // first message parameter
            ref Win32Api.tagWINDOWPOS lParam); // second message parameter

        [DllImport("User32.dll")]
        public static extern Int32 SendMessage(
            IntPtr hWnd,               // handle to destination window
            int Msg,                // message
            IntPtr wParam,             // first message parameter
            int lParam);            // second message parameter

        [DllImport("User32.dll")]
        public static extern Int32 SendMessage(
            IntPtr hWnd,               // handle to destination window
            int Msg,                // message
            IntPtr wParam,             // first message parameter
            long lParam);            // second message parameter

        [DllImport("User32.dll")]
        public static extern Int32 SendMessage(
            IntPtr hWnd,               // handle to destination window
            int Msg,                // message
            IntPtr wParam,             // first message parameter
            IntPtr lParam);            // second message parameter

        public const int WM_MOUSEMOVE = 0x0200;
        public const int WM_LBUTTONDOWN = 0x0201;
        public const int WM_LBUTTONUP = 0x0202;
        public const int WM_MOUSEACTIVATE = 0x0021;
        public const int WM_ACTIVATE = 0x0006;
        public const int MK_LBUTTON = 0x0001;
        public const int WM_NCHITTEST = 0x0084;
        public const int WM_SETCURSOR = 0x0020;
        public const int HT_CLIENT = 1;
        public const int WM_WINDOWPOSCHANGING = 0x0046;
        public const int SWP_NOSIZE = 0x0001;
        public const int SWP_NOMOVE = 0x0002;
        public const int WM_ACTIVATEAPP = 0x001C;
        public const int WM_NCACTIVATE = 0x0086;
        public const int WM_IME_SETCONTEXT = 0x0281;
        public const int WM_IME_NOTIFY = 0x0282;
        public const int WM_SETFOCUS = 0x0007;
        public const int WM_CAPTURECHANGED = 0x0215;
        public const int WM_KILLFOCUS = 0x0008;

        public static void Click(IntPtr mainWindowHandle, Point location)
        {
/*            SendMessage(mainWindowHandle, WM_NCHITTEST, IntPtr.Zero, 105 | (568 << 16));
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_SETCURSOR, (IntPtr)0x00422A84, 0x02000001);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_MOUSEMOVE, IntPtr.Zero, 105 | (568 << 16));
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_MOUSEACTIVATE, mainWindowHandle, 1 | (WM_LBUTTONDOWN << 16));
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_MOUSEACTIVATE, mainWindowHandle, 1 | (WM_LBUTTONDOWN << 16));
            Thread.Sleep(5);

            var postChange = new Win32Api.tagWINDOWPOS()
            {
                cx = 0,
                y = 0,
                x = 0,
                cy = 0,
                flags = SWP_NOSIZE | SWP_NOMOVE,
                hwnd = mainWindowHandle,
                hwndInsertAfter = (IntPtr)0x00580E3C
            };


            SendMessage(mainWindowHandle, WM_WINDOWPOSCHANGING, IntPtr.Zero, ref postChange);
            Thread.Sleep(5);

            var postChange2 = new Win32Api.tagWINDOWPOS()
            {
                cx = 105 + 1,
                y = 568,
                x = 105,
                cy = 568 + 1,
                flags = SWP_NOSIZE | SWP_NOMOVE | 1800,
                hwnd = mainWindowHandle,
                hwndInsertAfter = (IntPtr)0x00580E3C
            };


            SendMessage(mainWindowHandle, WM_WINDOWPOSCHANGING, IntPtr.Zero, ref postChange2);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_ACTIVATEAPP, (IntPtr)0x00000001, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_NCACTIVATE, (IntPtr)0x00000001, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_ACTIVATE, (IntPtr)0x00000002, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_IME_SETCONTEXT, (IntPtr)0x00000001, (IntPtr)(1 | (0xC000000F << 16)));
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_IME_NOTIFY, (IntPtr)0x00000002, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_SETFOCUS, (IntPtr)0, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_KILLFOCUS, (IntPtr)0x00232B2A, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_IME_SETCONTEXT, (IntPtr)0x00000000, (IntPtr)(1 | (0xC000000F << 16)));
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_IME_SETCONTEXT, (IntPtr)0x00000001, (IntPtr)(1 | (0xC000000F << 16)));
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_SETFOCUS, (IntPtr)0x00232B2A, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_IME_SETCONTEXT, (IntPtr)0x00000001, 0x0641);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_IME_NOTIFY, (IntPtr)0x00000002, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_SETFOCUS, (IntPtr)0, 0);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_SETCURSOR, (IntPtr)0x00422A84, 0x02000001);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_LBUTTONDOWN, (IntPtr)0x00000001, 105 | (568 << 16));
            Thread.Sleep(5);
            SendMessage(mainWindowHandle, WM_LBUTTONUP, (IntPtr)1, 105 | (568 << 16));
            Thread.Sleep(5);
            SendMessage(mainWindowHandle, WM_CAPTURECHANGED, IntPtr.Zero, IntPtr.Zero);
            Thread.Sleep(5);

            PostMessage(mainWindowHandle, WM_MOUSEMOVE, (IntPtr)0x00000001, (IntPtr)(105 | (568 << 16)));
            Thread.Sleep(5);
            PostMessage(mainWindowHandle, WM_MOUSEMOVE, (IntPtr)0x00000001, (IntPtr)(105 | (568 << 16)));
            Thread.Sleep(5);
            SendMessage(mainWindowHandle, WM_CAPTURECHANGED, IntPtr.Zero, IntPtr.Zero);
            Thread.Sleep(5);

            PostMessage(mainWindowHandle, WM_LBUTTONUP, IntPtr.Zero, (IntPtr)(105 | (568 << 16)));
            Thread.Sleep(5);
            SendMessage(mainWindowHandle, WM_CAPTURECHANGED, IntPtr.Zero, IntPtr.Zero);
            Thread.Sleep(5);

            SendMessage(mainWindowHandle, WM_NCHITTEST, IntPtr.Zero, (IntPtr)0x02DE0ACF);
            Thread.Sleep(5);*/

            //SendMessage(mainWindowHandle, WM_LBUTTONUP, IntPtr.Zero, (IntPtr)(105 | (568 << 16)));

            /*            Win32Api.PostMessage(mainWindowHandle, WM_MOUSEACTIVATE, mainWindowHandle,(IntPtr) (1 | (Mouse.WM_LBUTTONDOWN << 16)));
                        //mouse activate ?
                        Thread.Sleep(50);
                        Win32Api.PostMessage(mainWindowHandle, WM_ACTIVATE, (IntPtr)2, (IntPtr)(0 | (0 << 0)));
                        Thread.Sleep(50);
                        Win32Api.SendMessage(mainWindowHandle, WM_LBUTTONDOWN, MK_LBUTTON, (105 | (568 << 16)));
                        Thread.Sleep(50);
                        Win32Api.SendMessage(mainWindowHandle, WM_LBUTTONUP, 0, (105 | (568 << 16)));

                        Win32Api.PostMessage(mainWindowHandle, WM_ACTIVATE, (IntPtr)0, (IntPtr)(0 | (0 << 0)));*/

            //PostMessage(mainWindowHandle, Mouse.WM_MOUSEACTIVATE, mainWindowHandle, (IntPtr)(1 | (Mouse.WM_LBUTTONDOWN << 16)));
            //PostMessage(mainWindowHandle, Mouse.WM_LBUTTONDOWN, IntPtr.Zero,(IntPtr)(72 | (568 << 16))); // 72 568 x | (y << 16)
            //Thread.Sleep(50);
            //PostMessage(mainWindowHandle, Mouse.WM_LBUTTONUP, (IntPtr)72,(IntPtr)(72 | (568 << 16)));
        }
    }
}

Spy++ logs:
Log 1 Log 2

I've tried to recreate each Sent/Post, no success. Maybe i'm missing some vital info ? :D