Under some circumstances, content from one Firefox window hidden behind another leaks onto the top one. Reproducible in both Bionic (with Intel graphics) and Disco (in a VirtualBox VM), reporting this from Disco.

== Steps to reproduce ==
1. Open one Firefox window, drag it to the right side of screen to fill the right half, and navigate to https://www.twitch.tv/rifftrax
2. Open another Firefox window, maximize it on top of the first one, and use this topmost window to open https://www.youtube.com/watch?v=P5dxd-ocaE8 and expand the Youtube view to ’theatre’ mode

== What happens ==
White parts of content in Firefox window #1 cast a spectral shadow on the black parts of content in Firefox window #2. It’s quite subtle, but luckily can be caught in screenshots: see attachments below. Pausing the Youtube video seems to make the effect to go away (the transparency disappears).

== What I’d expect to happen ==
For the topmost window to be completely opaque, i.e. not to see anything from behind the topmost window whether the video is playing or not.

== Other info ==
Though I don’t think this is tied the two sites I’ve used as an example, they’re the first and only ones I’ve happened to encounter this with. I’ve yet to find other reports about this, apart from one /r/Fedora thread mentioning something similar: https://www.reddit.com/r/Fedora/comments/7m9m4h/youtube_videos_are_transparent_kind_of_in_firefox/

Untouched screenshot of top window revealing content from another window below

Same screenshot with added hints about see-through content

Hi Christopher, the apport-collected data above was gathered from my main desktop, which only has Intel graphics. (I mentioned the other system with Radeon just because it *didn’t* suffer from this problem despite having the same software. I no longer have access to that system so unfortunately I can’t provide the same logs from it for comparision.)

Since upgrading HWE from -lts-saucy to -lts-trusty, I have had recurring graphical glitches on screen, with short black horizontal lines appearing briefly on screen (on top of normal contents), particularly when switching between applications. The lines appear only for a few 100 ms before going away (just enough to register in your eye that there’s something there), so I’ve been trying to make a screen recording to capture it, but of course the phenomenon goes away when I do (perhaps RecordMyDesktop does something with the screen that makes it less likely to appear).

I have another 12.04 system with desktop Radeon graphics, and there -lts-trusty has not produced this issue so far (the one with the issue and the one I’m attaching the logs here from has Intel).

I don’t recall seeing this with -lts-saucy or other previous Xorg packages. It was so obvious right after upgrading that either it never occurred before or was so rare or quick to flash away that it didn’t register.

Helppo asennettava. Vakiojäähdyttimellä hiljainen ja viileä, mutta potkua piisaa. Viimeisetkin tehonrippeet suorittimestaan puristavat halunnevat K-mallin, mutta mikäli virtualisointi kiinnostaa, 3770:stä puolestaan löytyy Intelin VT-d.

Last week I replaced the internals of my desktop computer with a new ASUS P8H77-M PRO, Intel G2120 and 16 GB RAM. With one round of Memtest passed, I booted into my old Precise install and got bit hard by what appears to be Bug #993187: frequent hard lockups (multiple within a few hours of use). I installed linux-image-generic-lts-quantal (currently 3.5.0.22.29) and that seemed to resolve the lockups: I got more than two days of uptime (ending with an intended shutdown), half of which I was actively using the computer.

This morning, soon (half an hour?) after login, the kernel paniced with a reference to usb-storage (I’ll attach a picture). This was different from the lockups with the stock Precise (3.2) kernel: with them I never had any panics shown (only the frozen desktop) and the system had to be powered off to reboot, whereas with the panic here I could reboot using the chassis reset button.

There’s some USB activity in syslog just prior to the panic (Jan 7 at around 10:50), but I wasn’t using any USB devices at the time. I have used them with this kernel previously though, without issues, and currently am too (to transfer the panic picture from my phone). There’s a memory card reader/USB port panel (Akasa AK-ICR-17) permanently plugged into internal USB 2 and 3.

Sorry, the GM965 Express is the chipset, that one has a Mobile Intel GMA X3100 display adapter.

Confirming this on another G31 (MSI MS-7525). Haven’t seen similar on 5 other Precise setups I have, including laptops with Intel 855GM and GM965 Express on the graphics (the G31 has GMA 3100).

Bryce; no problem (and thanks for your working on this), for me the fbdev workaround is good enough to work and live with on this setup. If others affected by this feel differently, do take over with upstream.

Alright, I think this is safe to rule as invalid because the cause is most likely hardware failure: Oneiric boot media now also fails to boot here despite being the one used to install this system initially. I even went so far back as installing Jaunty (didn’t have anything more recent at hand, before Oneiric) and it also segfaults when X should start (though the graphical installer did work). I’ll still do tests if @Joseph disagrees (and has new ideas to test), but for now I’ll just settle for using fbdev (which seems to not trigger the issue).

I went back in Precise kernels [1] all the way back to 3.0.0-12.20. There seem to be no easy answers: now even 3.0.0-12.20 crashes with -intel.

I think this either means that the hardware’s broken, or that the issue has been lurking in kernels all the way back to (at least) 3.0.0-12.20, and was only triggered by some early Precise updates (during the time window I described above). As I said, it (definitely) wasn’t there when I filed Bug #903831 on 2011-12-13 (because I couldn’t have gotten far enough to trigger that bug with this on the way).

I’ll attach shots of current results with the early Precise kernels below just in case there’s anything useful there.

I think I’ll try ruling out hardware failure with Oneiric, either with the live disc (if that uses -intel) or by reinstalling.

* [1] https://launchpad.net/ubuntu/precise/+source/linux/