A powerbox is just like a normal file chooser
dialog box, except that it dynamically grants the
application the right to access the file that the
user picks. This helps provide security because
the application can be run without needing access
to all the user's files. Powerbox-for-Gtk patches
Gtk to replace GtkFileChooserDialog with a
powerbox. It is based on Plash, which provides a
restricted execution environment on Linux.
