The GNOME canvas is an engine for structured graphics that offers a rich 
imaging model, high performance rendering, and a powerful, high-level API. 
It offers a choice of two rendering back-ends:  one based on Xlib for 
extremely fast display, and another based on Libart, a sophisticated, 
antialiased, alpha-compositing engine.  Applications have a choice between 
the Xlib imaging model or a superset of the PostScript imaging model, 
depending on the level of graphic sophistication required.
