Here's the commit Tim found that fixes the API bug in question: http://gitweb.freedesktop.org/?p=cairo.git;a=commitdiff;h=a8ca155f83098c02fb8d3acc57b0492d5b753d54
"Correctly return the transformed bounding box for stroke/fill extents, instead of just transforming the two corners separately."
Here's the commit Tim found that fixes the API bug in question: http:// gitweb. freedesktop. org/?p= cairo.git; a=commitdiff; h=a8ca155f83098 c02fb8d3acc57b0 492d5b753d54
"Correctly return the transformed bounding box for stroke/fill extents,
instead of just transforming the two corners separately."