tried it with ubuntu's rdesktop via ssh tunnel on a gentoo box's x server and vice versa.
result: the problem lies in the interaction between rdesktop and the x server or clipboard.
(ubuntu's rdesktop can copy/paste on gentoo x server, gentoo's rdesktop can't on ubuntu x server, pure gentoo works as well)
did not test vncviewer yet, lacking a remote server.
tried it with ubuntu's rdesktop via ssh tunnel on a gentoo box's x server and vice versa.
result: the problem lies in the interaction between rdesktop and the x server or clipboard.
(ubuntu's rdesktop can copy/paste on gentoo x server, gentoo's rdesktop can't on ubuntu x server, pure gentoo works as well)
did not test vncviewer yet, lacking a remote server.