I connect via vnc tunnelled through ssh to my Linux desktop running Debian
unstable and run Thunderbird (aka Icedove).
Thunderbird crashes anytime I try to do anything that requires opening a new
windown. Here is the error message after the crash.

Error: Cairo does not yet support the requested image format:
        Depth: 8
        Alpha mask: 0x00000000
        Red   mask: 0x00000007
        Green mask: 0x00000038
        Blue  mask: 0x000000c0
Please file an enhacement request (quoting the above) at:
http://bugs.freedesktop.org/enter_bug.cgi?product=cairo
icedove-bin: /tmp/he/libcairo-1.2.4-3.1/src/cairo-image-surface.c:155:
_cairo_format_from_pixman_format: Assertion `NOT_REACHED' failed.
/usr/lib/icedove/run-mozilla.sh: line 131: 19692 Aborted                 "$prog"
${1+"$@"}