(bool) false == 0 == (const char*) NULL
error: ISO C++ says that these are ambiguous, even though the worst
conversion for the first is better than the worst conversion for the second:
actions.h:92: note: candidate 1: Glib::RefPtr<Gtk::Action> ActionManager::get_action(const char*, const char*, bool)
actions.h:91: note: candidate 2: Glib::RefPtr<Gtk::Action> ActionManager::get_action(const std::string&, bool)
cd70c6bda5