SPMediaKeyTap abstracts a CGEventHook and other nastiness in order to give you a relatively simple API to receive media key events (prev/next/playpause, on F7 to F9 on modern MacBook Pros) exclusively, without them reaching other applications like iTunes. SPMediaKeyTap is clever enough to resign its exclusive lock on media keys by looking for which application was active most recently: if that application is in SPMediaKeyTap's whitelist, it will resign the keys. This is similar to the behavior of Apple's applications collaborating on media key handling exclusivity, but unfortunately, Apple is not exposing any APIs allowing third-parties to join in on this collaboration. For now, the whitelist is just a hardcoded array in +[SPMediaKeyTap defaultMediaKeyUserBundleIdentifiers]. If your app starts using SPMediaKeyTap, please mail me your bundle ID, and I'll include it in the canonical repository. This is a bad solution; a better solution would be to use distributed notifications to collaborate in creating this whitelist at runtime. Hopefully someone'll have the time and energy to write this soon.