Method

The Citrix client (for connecting to a remote Citrix server) works fine under Ubuntu 7.04 with the following modification to the file "/usr/lib/ICAClient/wfica.sh":

#!/bin/sh
xset fp rehash
ICAROOT=/usr/lib/ICAClient
export ICAROOT
$ICAROOT/wfica -file $1

The additional line is the "xset fp rehash", which tells the font manager to re-calculate the font paths. This avoids the core dump due to X not finding the correct set of fonts.
After this, simply tell Firefox to open *.ica files with wfica.sh.