GDK_WINDOW_HWND() calls from outside gdk calls ensure_native_window, but we really want the HWND of the impl window, so call the new gdk_win32_window_get_impl_hwnd() instead.
GDK_WINDOW_HWND() calls from outside gdk calls ensure_native_window, but we really want the HWND of the impl window, so call the new gdk_win32_window_get_impl_hwnd() instead.