After logging into a session an error report pops up telling the user that xprop has crashed. Haven't tried to get any detailed explanation as to why, but the offending command is apparently:
/opt/thinlinc/libexec/xprop -root 32x \ $0\\n_NET_SUPPORTING_WM_CHECK
The original report was for Ubuntu 13.04 Beta, but I also get this on Fedora 18.
Our ancient xprop is horribly buggy. It abort():s whenever a property doesn't exist on a window. I'm amazed we haven't run in to this earlier.
The xprop in Fedora 18 works fine, so I think we'll just try an upgrade.
xprop upgraded in r27105.
Unable to reproduce using the new xprop on Ubuntu 13.04, so assuming that upgrading it has solved the problem. Closing.