Sometimes Mac's accessibility permissions becomes corrupted, and weird things start to happen.

For example, Steam applications will complain that accessibility permissions are required, even though they apparently are already granted.

To fix this, reset the accessibility permissions cache:

1. Launch `Terminal.app`
2. Enter `tccutil reset Accessibility`
3. Quit Terminal
4. Launch `System Preferences`
5. Select `Security & Privacy`
6. Select the `Privacy` tab
7. Unlock the console.
8. Add the appropriate application (e.g. `/Applications/Steam.app`).