gistfile1.txt

  var hwndSource = HwndSource.FromHwnd(handle);
  if (hwndSource != null)
  {
      hwndSource.AddHook(WindowProc);
  }

WinAPI.ShowWindowAsync(new WindowInteropHelper(OverlayForm).Handle, 0);

private IntPtr WindowProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            switch (msg)
            {
                case 0x0003:
                    uint uFlags = WinAPI.SWP_NOACTIVATE | WinAPI.SWP_NOZORDER;

                    int parent = Application.ActiveWindow.Hwnd;
                    System.Drawing.Rectangle rect = new System.Drawing.Rectangle();
                    WinAPI.GetWindowRect((IntPtr)parent, ref rect);
                    WinAPI.SetWindowPos((uint)hwnd.ToInt32(), parent, 0, 0, rect.Right, rect.Bottom, uFlags);
                    break;
            }
            return (IntPtr)0;
        }

var lpwndpl = new WINDOWPLACEMENT();
lpwndpl.rcNormalPosition = new System.Drawing.Rectangle(rect.Left, rect.Top, rect.Width, rect.Height);
lpwndpl.length = System.Runtime.InteropServices.Marshal.SizeOf(lpwndpl);
WinAPI.SetWindowPlacement((uint)handle.ToInt32(), ref lpwndpl);

WinAPI.HookProc HookProcedure = new WinAPI.HookProc(ThisAddIn.HookProc);
WinAPI.SetWindowsHookEx(0x0003, HookProcedure, (IntPtr)0, AppDomain.GetCurrentThreadId());

public delegate int HookProc(int nCode, IntPtr wParam, IntPtr lParam);

public static IntPtr ParentProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled) {
public static int HookProc(int nCode, IntPtr wParam, IntPtr lParam) {
System.Diagnostics.Debug.WriteLine(nCode);
return 0;
}

[DllImport("user32.dll")]
public static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hWnd, int id);