Comment 63 for bug 501393

(In reply to comment #60)
> I suppose I can just not add the action callback if the server doesn't support
> them.

So:

#define NOTIFY_CAPS_ACTIONS_KEY "actions"

GList *server_caps = notify_get_server_caps();
if (g_list_find (server_caps, NOTIFY_CAPS_ACTIONS_KEY))
...

if you do this, consider to cache the result somehow as you would otherwise do another dbus call for each notification.