private int OpenFileSubClass ( IntPtr hWnd, uint uMsg, IntPtr wParam, IntPtr lParam, IntPtr uIdSubclass, uint dwRefData ) { switch (uMsg) { case InteropUtil.WM_PARENTNOTIFY: { unchecked { var id = lParam.GetDlgCtrlID(); if (LOW((uint)wParam) == InteropUtil.WM_CREATE && (id == InteropUtil.ID_FileList || id == 0)) { lParam.SetWindowSubclass(m_defViewSubClassDelegate, 0, 0); } } break; } } return hWnd.DefSubclassProc(uMsg, wParam, lParam); }