Some documentation on how the GTK+ port is designed.

State classes:

StyleManager keeps track of what user-defined styles the application
knows about, and which one is currently "active".  The active style
is used when creating new nodes.

Preambles keeps track of the preambles used for previews.


GUI classes:

MainWindow is the core class that manages the application as a whole.
It manages the main GtkWindow and is generally responsible for loading
the various UI elements.  It also keeps track of the main application
configuration file, the user-defined styles (via StyleManager) and the
custom preambles (via Preambles).

The Menu class manages the menu and toolbar for MainWindow.  It uses
GtkUiManager to load these from an XML description, and deals with the
GTK+ callbacks for the various actions.