cairo and vnc - font problems

[XeHonk]

Hi,

I've got problems with xchat and gaim running in net-misc/vnc.
After upgrading to cairo 1.3.10, my fonts ins vnc started showing strange graphics errors: http://honk.ath.cx/files/vnc/vnc.png.
After upgrading to 1.3.12, the applications using cairo just segfaulted (core dump: http://honk.ath.cx/files/vnc/core.txt)
After downgrading to 1.2.4 everything is fine again.

The problem only occurs in net-misc/vnc btw, using tightvnc or xf4vnc doesnt show this problem (they've got other problems though, that prevent me from using 'em: xf4vnc does not properly support copy&paste and tightvnc will crash xchat if I turn on the transparent background).

I'd be grateful for any hints on what I'm doing wrong. :)