B.5.1.1. GTK+ (GIMP toolkit)

B.5.1.3. XML/DOM libraries

B.5.1.4. The Canvas/Libart engines

The Canvas is designed to be an extensible, but generic, display engine. The Gnumeric spreadsheet application, for example, uses the Canvas to display the spreadsheet but provides its own custom extensions. Applications like the GNOME calendar and the Midnight Commander file manager use the basic functionality of the canvas in their displays.

Libart is a vector manipulation and rendering engine that uses anti-aliasing and alpha-compositing. The canvas is built upon Libart, which it uses to render its objects into an RGB buffer. Libart makes it easy for the canvas to create anti-aliased, alpha-composited output. Libart provides a superset of the PostScript imaging model for extremely high-quality output.

B.5.1.5. The Bonobo component and document model

It's a framework similar in concept to Microsoft's Object Linking and Embedding (OLE). Bonobo allows programmers to create reusable software component objects (similar to Active X Controls). It is also a document model that defines a system where these objects can seamlessly interact within shared container documents (Similar to Linking and Embedding).

To use an example that many people are familiar with, in Microsoft Office, an Excel document can be embedded within a Word document. The Word document in this case is a container document. It contains both the Word data and the Excel data. However, clicking on the Excel data allows you to work on it as though you were working in Excel, even though it is embedded in the Word document. The Excel application functions as a piece of component software, creating the illusion that the user is only interacting with one application.

Bonobo is a set of CORBA interfaces that are necessary for component design and interaction. The Bonobo interfaces are both language- and toolkit-independent, and Bonobo components can be both written and used in any language. The reference implementation of Bonobo is based on the Gtk object system and maps CORBA interfaces to Gtk objects which can be easily manipulated by the application author.

Note that while many programmers associate OLE with great complexity, much of that is due to the way Microsoft was forced to design OLE so that it would work well with Windows. While sharing much of the same functionality as OLE, Bonobo is inherently a much simpler system to understand and design software with.