So there is a bug in Synergy where if you’ve got a Windows box as a synergy client, and you attempt to rdp/rdesktop to another windows box from that windows-synergy-client box, the Right Shift key doesn’t work.
The following command will map the right shift to the left shift in X and work around this bug:
xmodmap -e “keycode 62 = Shift_L NoSymbol Shift_L NoSymbol Shift_L”
You may want to run xev and make sure your right-shift is keycode 62.
Useful Reference: http://www.columbia.edu/~djv/docs/keyremap.html