Remote-Clipboard-Support for VNC-Applications

Transferring the clipboard-content to the remote vnc-system is still not possible. It does not seem to be a problem of the "desktop-sharing" (not only) as the problem remains when connecting to a win-machine (which runs the old at&t-vnc, which supports clipboards), but of the clients (tried terminal-server-client, tight-vnc, too).
Ok, concluding: I'd like to mark some text on my machine, do a "copy" and then an "insert" of this text on an machine connected through vnc.