Thanks to all the replies. With the help of Rex, we've discovered an interesting bug in the xprop utility and I have attempted to make contact with the author.
Vik :v) -- /"\ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . /"\ \ / ASCII Ribbon Campaign One of The Olliver Family \ / X - NO HTML/RTF in e-mail http://olliver.family.gen.nz X / \ - NO MSWord docs in e-mail Public PGP key available there / \
