Not really a solution to literal "grabbing windows of programs already running", but still…
Use xpra
.
On X11, it is also known as screen for X11: it allows you to run programs, usually on a remote host, direct their display to your local machine, and then to disconnect from these programs and reconnect from the same or another machine, without losing any state.
[…]
Xpra also allows forwarding of sound, clipboard and printing services.
Sessions can be accessed over SSH, or password protected over plain TCP sockets with or without SSL.
It has to be installed, configured and started beforehand, just like screen
or tmux
for console applications. You have to run your program via xpra
in the first place, then you can do the magic of (re)connecting from different machines.
xpra
is available as xpra
package at least in Debian and Ubuntu. I have used it few times. The performance was better than for plain X forwarding.
Examples are here. The following are from man xpra
on my Kubuntu:
xpra start :7
Start an xpra
server using display number :7
.
DISPLAY=:7 firefox
Start firefox
running inside the xpra
server. Run this on the host where xpra
was started or in terminal forwarded by xpra
. No window will appear until you attach with xpra attach
.
You run the above examples on your A. Then you can attach directly from A:
xpra attach :7
Attach to the xpra
server that is using local display number :7
. Any apps running on that server will appear on your screen.
or from your B:
xpra attach ssh:foo@frodo:7
Use ssh
to attach to the xpra
server that is running on machine frodo
as user foo
and using display :7
. Any apps running on that server will appear on your local screen.
xpra
, see answer below.