One could extend the application to save and load the tree's
contents. The XBEL (XML Bookmark Exchange Language) would be
very ideal for this.
Make your applications user-friendly: Every text field which requires
a filename or a path should accept drops from file managers.
It is easy to create a class with a
prepareFileDrops function, which completely sets
up an GtkEntry to accepts file drops and
changes the field's content in the case of a drop.