If you would like the feature reinstated, please email email@example.com. If there are enough responses then the feature will be added again.
It prevents unauthorised users from using the mouse or keyboard on the machine. Any attempts to use the mouse or keyboard will present a password dialog window.
The software can also prevent Command-Option-Escape (Force Quit), the debugger (MacsBug or ROM Debugger) and restart/shutdown using the Power button.
In order to function, the feature has to install a system extension into your Extensions folder. OAT will do this for you when you turn it on for the first time. If you have any difficulties with the feature, just remove the extension (called 'Machine Lock').
One option of interest is the 'Dim Screens' feature. This only works for indexed-colour screens (ie 8 bit or less), and dims the screen to 50% of its normal value when the keyboard and mouse are locked out.