Agar is a toolkit for graphical applications. It features a modern GUI system with an unobtrusive API. Agar can use different graphics interfaces, such as SDL and OpenGL, and it has been ported to numerous platforms, including game consoles and embedded systems. Agar is implemented in C, but can be used from other languages.
JGraph is a free, mature, and robust Java diagramming library. It contains all the graph visualization, layout, and interaction functionality you might expect in a graph library, including multiple views, layering, zoom, drag and drop, undo, automatic expanding and collapsing, routing, and layouts. You can create workflow editors, BPMN, CAD tools, network diagrams, database visualization tools, and more. It is fully documented, including examples, and has an active support community.
DirectFB is a thin library that provides developers with hardware graphics acceleration, input device handling and abstraction, an integrated windowing system with support for translucent windows and multiple display layers on top of the Linux framebuffer device. It is a complete hardware abstraction layer with software fallbacks for every graphics operation that is not supported by the underlying hardware.