tool to detach/reattach running X programs

 Xpra gives you the functionality of GNU Screen for X applications.
 .
 It allows the user to view remote X applications on their local machine, and
 disconnect and reconnect from the remote machine without losing the state of
 the running applications.
 .
 Unlike VNC, these applications are "rootless". They appear as individual
 windows inside your window manager rather than being contained within a single
 window.