[cairo] in_fill hit test and matrix transforms

[Donn]

> An identity matrix is one with no transformation.
Thanks.

>   cr.save ()
>   cr.identity_matrix ()
>   cr.in_fill (...)
>   cr.restore ()
Trying that leads to no result I can see. Since the path is invisible, it's 
hard to say where it is on the page, but mousing around finds no hits.

I am having success by re-doing the matrix when I'm done checking for the hit.

Thanks.
\d