Hardly one of the users of OS X do not know about the functionality of the Quick Look.
However, few people suspect that Quick Look has an interesting hidden feature that is disabled by default.
This hidden feature is called “regime of x-ray folders”, and it works only in OS X 10.5 and 10.6. After its activation, Quick Look, when viewing a folder, will show not only general information, but also its content.
To activate this mode, simply follow the following:
1. run terminal
2. command defaults write com.apple.finder QLEnableXRayFolders 1
3. command killall Finder