RE: cross-platform client: I'd bet Qt.
you bet right ;) python + qt4 (one of the team member)
Qt ? No thank you... Maybe in a 64bit standalone version.
BTW: * How this will work in some Window Manager like dwm ? * What if I have no file manager installed ? * Can I use without using the mouse ?
I Guess its no to all of those questions. Maybe you're not our target :/
Which technology did you used for the cross-platform client ?
Good luck!