Free gaphas software for linux

Gaphas is a diagramming widget for GTK+ written in Python.
It is a MVC canvas that uses Cairo_ for rendering. One of the nicer things of this widget is that the user (model) is not bothered with bounding box calculations: this is all done through Cairo.
Main features:
- Each item has its own separate coordinate space (easy when items are rotated).
- Items on the canvas can be connected to each other. Connections are maintained by a linear constraint solver.
- Multiple views on one Canvas.
- What is drawn is determined by Painters. Multiple painters can be used and painters can be stacked.
- User interaction is handled by Tools. Tools can be stacked.
- Versatile undo/redo system