Screen blanking on displays outside of active tty

[Christian Chapman]

Hello, all

If you start an xsession on another vt like this:

xinit -- vt01 :128

then switch back to :0, then try and screencap :128 (I used xwd) , the
resulting capture is a black rectangle. It seems that xsessions blank
out when their tty loses 'focus.' Is there a way to disable this
behavior? My script needs to be able to screencap such an xsession.

Thank you!