Hey,

Lets say I started an application (say, aMule) on my local system,
and after a while I want it to display on a remote system (using X forwarding).

Is there a way to switch the DISPLAY without terminating the application and starting over?

Is there a way to display the application on my local system and on the remote system simultanously?

Thanks
Fiod

My understanding of how X works says that neither is possible if you only use X server. For the first task you could use xmove - it is a virtual X server that can display its clients on any accessible X display, either local or remote (but local should be 127.0.0.1:0, not just :0 - and some distributions disable TCP connections to X server by default). If you want to display an application on two displays at once, it looks like you need VNC server and client (I use tightVNC and find it comfortable). And now a bonus: you can just share all your X11 session via VNC using x11vnc. So application runs at your local display, accepts connections from 127.0.0.1 (-localhost switch), and whenever you need you tunnel port 5900 over SSH and launch vncviewer (VNC is better than X11 over network, because X11 was designed for fast LAN).

Use VNC ....