Foreign struct conversion fails for cairo.Matrix

Submitted by Tristan Brindle

Link to original bug (#651043)

Description

The CanvasItem API in GooCanvas has methods which involve Cairo matrices. In trying to put together GI-based bindings for GooCanvas, I've run into a problem where the introspected cairo.Matrix type can't be interchanged with the PyCairo Matrix type, unlike cairo.Context or cairo.Surface.

Trying to do so raises a TypeError:

Traceback (most recent call last):
  File "./cairo-matrix-test.py", line 12, in `<module>`
    t.set_transform(matrix)
  File "/usr/lib64/python2.7/site-packages/gi/types.py", line 44, in function
    return info.invoke(*args)
TypeError: Couldn't find conversion for foreign struct 'cairo.Matrix'