I experienced a different problem (bug 32457 - gnome-screensaver activates while playing SDL games) while using DOSBox, and when I deactivated the screensaver, I lost mouse click and keyboard input, just like with this tsclient problem. The cursor still moved, so the X server wasn't totally frozen, as with tsclient. Only CTRL-ALT-Backspace worked.
Seems to me that this bug is in gnome-screensaver, and is invoked by certain apps like DOSBox (libSDL??) and tsclient (rdesktop).
I'd like to help resolve this bug. Do I need to self compile gnome-screensaver with debug output support, or is there something else I can do? I'm not a strong programmer, just a power user.