SimpleList is a simple interface to the powerful but complex
Gtk2::TreeView and Gtk2::ListStore combination, implementing using
tied arrays to make thing simple and easy.

Gtk2 has a powerful, but complex MVC (Model, View, Controller) system
used to implement list and tree widgets. Gtk2::Ex::Simple::List
automates the complex setup work and allows you to treat the list
model as a more natural list of lists structure.
