Hi Moshe! I find this bug unreproducible. Also kate is one of the main apps included in KDE, so if this is a packaging/app problem, more people would have certainly filled this bug before, or replied to it.
Lisandro, Thank you for your help and suggestions.I find that I cannot perform a full-upgrade (dist-upgrade) on my system; aptitude cannot resolve the all the conflicts without removing what appears to be all of kde-standard.
Furthermore, a reboot of the system seems to have restored kate's filesystem access and cleared the problem. (The reboot was after a crash of all open windows, which tells me that I have instability somewhere.)
Please close this bug. I will resolve my local configuration problems; if the problem reappears I will open a new ticket.
Again, I very much appreciate your help and patience. -- Moshe Yudkowsky * moshe@pobox.com * www.pobox.com/~moshe