DWORD dwExStyle = GetWindowLong(hWnd, GWL_STYLE);
dwExStyle &= ~(WS_VISIBLE);
dwExStyle |= WS_EX_TOOLWINDOW;
dwExStyle &= ~(WS_EX_APPWINDOW);
SetWindowLong(hWnd, GWL_STYLE, dwExStyle);
ShowWindow(hWnd, SW_SHOW);
ShowWindow(hWnd, SW_HIDE);
UpdateWindow(hWnd);