Powerbox
A file powerbox is a file dialog that will dynamically grant the application that opened it the right to access the file that the user chooses.
This means that an application does not have to run with the user's full authority. In other words, the application does not have to have the right to access all the user's files. An important aspect of the powerbox interface is that it can look to the user just like any other insecure file dialog, but can act to protect the bulk of the user's files from potentially untrustworthy software such as Trojan horses or other forms of Malware.
With a powerbox system, the file dialog is implemented as a trusted part of the system. It runs in a protection domain separate from the application. The powerbox component has access to all the user's files, whereas the application does not.
Powerbox systems have been implemented in Apple Mac OS X Lion.
Read more about this topic: File Dialog