Hrm... Just had an unusual experience!
After doing the (above) upgrades, this machine started dropping into Fallback Mode, when awaking from a screensaver blanking event.
That is, I would walk away from this machine for a few minutes (logged into GS) -- the screensaver would blank the display -- but, when I woke it up, I was in Fallback Mode, not GS.
I started to compose a post about this situation, but got distracted with updating my Facebook account. LoL!
When I finally got back to sorting it, I noticed there was a single upgrade available in Synaptic... gnome-screensaver 3.6.1-0ubuntu3. Hello?!?!?
After upgrading gnome-screensaver, I saw a post by zika (in another thread) pointing to this video:
http://mirror.linux.org.au/linux.con...land_and_X.mp4
"Perfect test," me thinks...
I watched the video, sort of. I fell asleep several times, but every time I awoke, the video was still playing, e.g. as if Caffeine was running in the background (which it wasn't).
"Great, now the screensaver is broken!"
To my surprise, after the video completed, my monitor gently faded to black (screensaver blanked the display). When I moved the mouse, the panel was missing, there was no transparency in Conky, and most everything else was missing. My immediate thought was, "Okay, we're in Fallback Mode again, but... This time, everything eventually popped back up, one component at a time. And, I was still in GS.
If that wasn't spooky enough, that's basically what the video was talking about... the random way xorg-server draws windows, borders, et cetera (vs Wayland).
Anyway, unless I'm still dreaming, it looks like the new gnome-screensaver has some method of preventing your computer from falling asleep while watching videos. The jury is still out, on GS coming back up, or Fallback Mode.
Anybody else experience this?