Code review comment for lp:~robertcarr/mir/client-focus-notifications

198 + virtual ~IPCSemaphore();

Prefer a non-virtual, noexcept destructor

~~~~

549 + client->handler->handle_event(ev);

If "ev" were given the more meaningful name the sheer repetitiveness would be even more apparent:

    client->handler->handle_event(event);

You can see it here too:

948 + event_sink->handle_event(any_event);

s/handle_event/handle/ would be an improvement.

~~~~

98 + std::weak_ptr<Surface> focus_surface;

What is the purpose of this? The name isn't clear, and the usage is entirely at member function scope (so why use a member variable).