File navigation in the IDE does not allow one to navigate into bundle files (e.g., to get inside a .app bundle).  You
might want to do this, for instance, to add a jar from an application (like OpenOffice) to your project, or to build a
library wrapper around jars found in a .app bundle.

But, when you are doing file navigation in any file browser window, when you get to a '.app' it adds that directory as
if it were a file, and doesn't let you drill down into the directory structure that is contained within the bundle.