From Kevin Gessner:
FunctionFlip individually controls your MacBook or MacBook Pro's function keys, turning special keys back to regular F-keys, or vice-versa. FunctionFlip is a preference pane; you'll find it in the "Other" category in System Preferences.
FunctionFlip's purpose is simply to disable the special features - rewind, play, mute, etc. - on the function keys. For example, if you "flip" F7, F8, and F9, those keys - only those keys - will revert back to normal F keys. Press the fn key with the special key to get the special function back. That is, the "special" and "normal" functions are flipped.
What's new in this version:
Support Yosemite and newer Mac keyboards.