After my last upgrade, about a week or so ago, this bug has mostly
disappeared. My machine reliably wakes up from suspension with both
monitors working, and not mirrored. The only odd thing is that,
although I start out with different desktop images (photographs) on the
two monitors, once I wake the computer up from suspend, the second
screen has the same desktop image as the first one. This is not a
problem, of course, but I thought I should report it.
I'm sorry that I don't have the exact date when I upgraded and found the
problem fixed, but I had become accustomed to shutting the computer off
rather than suspending it, and had disabled suspending after a period of
inactivity. I now have re-enabled both and it works great.
A further upgrade (to the current testing (stretch)) last night (8/9/16)
seems to continue to work correctly, although the desktop image on
screen #2 is still changing to the image from screen #1 after waking the
machine up. Neither of these upgrades replaced any xfce4 packages, or
any xorg packages (I don't think it did, anyway). The kernel was
upgraded to, I believe, linux-image-4.6.0-1-amd64_4.6.4-1_amd64.deb (I'm
not on that computer right now, but this one was upgraded at the same
time, and has the same architecture --- but only one monitor).
--
David L. Johnson
Department of Mathematics
Lehigh University
