I just saw a post on another site warning about thieves who can break into a garage by slipping a coat hanger through a gap at the door top, then releasing the safety catch using just a small amount of pull-pressure.
The safety tip was to secure the release catch using a zip-lock light enough to foil a coat hanger, but weak enough to be broken by someone inside during an actual emergency.
Here's a
YouTube video explaining the technique.
Regards,
--ghp