Win API Kaynak

        [DllImport("user32.dll")]
        static extern IntPtr GetForegroundWindow();


        [DllImport("user32.dll", EntryPoint = "FindWindowEx", CharSet = CharSet.Unicode)]
        static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string lclassName, string windowTitle);


        [DllImport("User32.Dll")]
        public static extern void GetClassName(IntPtr h, StringBuilder s, int nMaxCount);


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

        public const int WM_SYSCOMMAND = 0x0112;
        public const int SC_CLOSE = 0xF060;

        [DllImport("user32.dll")]
        static extern int GetWindowText(IntPtr hWnd, StringBuilder text, int count);

        private const int BN_CLICKED = 245;

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern int SendMessage(int hWnd, int msg, int wParam, IntPtr lParam);
        public enum SendMessageTimeoutFlags : uint
        {
            SMTO_NORMAL = 0x0000,
            SMTO_BLOCK = 0x0001,
            SMTO_ABORTIFHUNG = 0x0002,
            SMTO_NOTIMEOUTIFNOTHUNG = 0x0008
        }


        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        private static extern uint RegisterWindowMessage(string lpString);


        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        private static extern IntPtr SendMessageTimeout(IntPtr hWnd, uint Msg, UIntPtr wParam, UIntPtr lParam, SendMessageTimeoutFlags fuFlags, uint uTimeout, out UIntPtr lpdwResult);

        [DllImport("oleacc.dll", PreserveSig = false)]
        [return: MarshalAs(UnmanagedType.Interface)]
        private static extern object ObjectFromLresult(UIntPtr lResult, [MarshalAs(UnmanagedType.LPStruct)] Guid refiid, IntPtr wParam);
        const int WM_GETTEXT = 0x000D;

        public IHTMLDocument2 GetIEHTMLDocument2FromWindowHandle(IntPtr handle)
        {
            UIntPtr result;
            uint message;
            IHTMLDocument2 htmlDocument = null;

            try
            {
                if (handle != IntPtr.Zero)
                {

                    //  message = RegisterWindowMessage("WM_HTML_GETOBJECT");
                    message = RegisterWindowMessage("WM_GETTEXT");

                    SendMessageTimeout(handle, message, UIntPtr.Zero, UIntPtr.Zero, SendMessageTimeoutFlags.SMTO_ABORTIFHUNG, 1000, out result);

                    if (result != UIntPtr.Zero)
                    {
                        htmlDocument = ObjectFromLresult(result, typeof(IHTMLDocument).GUID, IntPtr.Zero) as IHTMLDocument2;
                    }
                }
            }
            catch (Exception)
            {
                throw;
            }
            return htmlDocument;
        }




        [DllImport("user32.dll")]
        static extern void mouse_event(int dwFlags, int dx, int dy,
                              int dwData, int dwExtraInfo);

        [Flags]
        public enum MouseEventFlags
        {
            LEFTDOWN = 0x00000002,
            LEFTUP = 0x00000004,
            MIDDLEDOWN = 0x00000020,
            MIDDLEUP = 0x00000040,
            MOVE = 0x00000001,
            ABSOLUTE = 0x00008000,
            RIGHTDOWN = 0x00000008,
            RIGHTUP = 0x00000010
        }


        public void LeftClick(int x, int y)
        {
            Cursor.Position = new System.Drawing.Point(x, y);
            mouse_event((int)(MouseEventFlags.LEFTDOWN), 0, 0, 0, 0);
            mouse_event((int)(MouseEventFlags.LEFTUP), 0, 0, 0, 0);
        }