Questions about extending Karabiner's functionality through use of private.xml
Karabiner, formerly called KeyRemap4MacBook, is an application for Mac OS X that allows the user to take complete control of keyboards and mice by setting up custom keybindings. It ships with hundreds of built-in bindings, fixes for common annoyances or broken drivers, and examples.
Bindings can be as simple as switching the Tab and the Return keys, or as complex as defining series of keystrokes and simulated mouse clicks and movements to occur in response to a single user action.
Karabiner is extended through an XML-based file, private.xml, that defines custom mouse and keyboard bindings.