"OnyX runs scripts and uses system commands that require the application to control your computer. Otherwise, some options may not work correctly.
To add OnyX to the list of applications allowed to control your computer:
1. Open the System Preferences pane and click the Security & Privacy icon.
2. Click the Privacy tab, then select Accessibility in the list located to the left.
3. If the preferences pane is locked, click the lock icon and enter your password.
4. From the Finder, drag the OnyX icon into the applications list located in the right-half of the preferences pane. (The checkbox must be selected.)
5. Close the preferences pane.
Note: OnyX never accesses your personal data (contacts, calendars, reminders, and so on)."
Ei vaan valkene nyt mitenkään, ei ole mitään ohjelmalistaa mihin tuon raahaisi

EDIT no joo, pitäsi lukea tarkemmin nuo ohjeet, kyllähän tuon saa asennettua mutta vähän epäilyttää tuo "Allow Onyx to control your Mac" ja miksi se on nyt näin.