Doing this properly requires the feature I talked about yesterday: the ability for the windowing system to tell the application that it's about to lose its graphics context and to recreate it. This would allow the windowing system to move the window behind the application's back, and the application would simply need to reacquire a graphics context handle and recreate any server-side resources. Windows apps have been doing this for years; it's not hard (though it can be annoying to have to deal with if you don't think about it from day one), and it lets the OS have a lot more flexibility in how it manages graphics contexts. X11 cannot do this; Wayland maybe can.
Moving windows between x-servers is possible and has been for a long time. It is called x2x. Just google it.
I'm not sure if most extensions work with this though. Probably not any of the video extensions, but maybe opengl does work. We have aiglx (accelated indirect glx ) for a few years now after all.
This is nothing like window transfer. However, I am starting to doubt, what OP had truly in mind when asking the question. Maybe I am too infected with the concept I have seen in a film.x2x allows the console (keyboard and mouse) on one X terminal to be used to control another X terminal. It also provides ancillary functions like clipboard sharing.
DMX did something like that, too (unified several X screens on different machines to one big screen).
I see how this idea is difficult to implement. Maybe the way could be sending window's data to both xservers having them both render the window (with 3D acceleration) (always, or just when the window is going through screen edge). Or maybe if there is a way to force graphic card to rendr image to created framebuffer that covers display area of both xservers, we can send just pixel data through network.. perhaps 10Gb/s ethernet or thunderbolt or just use 1Gb/s interface (which would cause slow refresh rate on one X).
Last edited by Grawp; 04-19-2012 at 12:32 PM.
All I can do for you now is ask one more control question. Then I am out of my knowledge jurisdiction. Do you want to have the desktop plane extended on all displays? Good luck with that. I sign off.
Oh yeah I want the desktop plane extended on all displays.
I'll try to reformulate the problem. Is it possible to add virtual display to Xorg? From this http://www.thinkwiki.org/wiki/Xorg_RandR_1.2#Summing_up I understand that there is already a virtual screen. I just really need to add there a virtual display so I can sample it by xwd.
I've just found xserver-xorg-video-dummy driver. I guess by description that it's what I've been looking for. I'll make a multimonitor network setup with x11vnc and I may post some results here.