GdkDisplay *display;
GdkDeviceManager *device_manager;
GList *devices, *d;

display = gtk_widget_get_display (widget);
device_manager = gdk_display_get_device_manager (display);

devices = gdk_device_manager_get_devices (device_manager);

for (d = devices; d != NULL; d = d->next)
  {
    GdkDevice *device;

    device = d->data;
  }

g_list_free (devices);