is a layer above the existing toolkits available (Win32 API, GTK, Cocoa, ...). The result is that applications look and function like the user expects on their respective system. Mozilla Public License
a 2D graphics library, support for multiple output devices. (output targets include the X Window System, Win32, image buffers, PostScript, PDF, and SVG file output. Experimental backends OpenGL (through glitz), Quartz, and XCB.