[cairo] Changing color mid-stroke

[AngryZealot]

Hi all,

I'm wondering if there's a way to change color in the middle of a
cairo_line_to operation, or at least a workable way to fake the
result. For an example of what I'd like to produce, see the picture
here: http://i208.photobucket.com/albums/bb305/AngryZealot/miter.jpg

Basically I need a way to split the joining piece between two
arbitrary line segments (ie, the joining angle is not fixed). I
realize this is somewhat unusual (neither Inkscape nor Adobe
Illustrator can do it without outlining the stroke). If somebody more
familiar with cairo has any ideas, it would be much appreciated.