Code review comment for lp://staging/~jjed/unity/tooltips-redux

+#define NULL_ICON (AbstractLauncherIcon::Ptr)nullptr

Don't do this please :)

314 +void TooltipManager::StopTimer() {
315 + hover_timer_.reset(new glib::Timeout(TOOLTIPS_SHOW_TIMEOUT_LENGTH));
316 +}

Is this the right way to stop the timeout?

Also I think you can unit test the new class ;)