How to prevent/change system-wide Keyboard / Mouse events under Mac OS X?

Question

I find two method to handle global events on Mac OS:

1. NSEvent.addGlobalMonitorForEvents only get a copy of origin event, can monitor, but not change or prevent.

Answer 1

You can use Quartz Event Taps for that. In order to monitor/change/block keyboard events, your process will need to be trusted for Accessibility access.