Single green pixel in upper-left corner -- only in Qubes

[Andrew David Wong]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Does anyone else have a single green pixel in the upper-left corner of
their screen? I just noticed that both of my Qubes installations on
separate hardware have this, yet the same monitors under a different OS
do not. It's easiest to see against a dark (e.g., completely black)
background.

One of my Qubes machines is a workstation with three monitors. The green
pixel starts out in the upper-left corner of the left-hand monitor. If I
disable the monitors one-by-one, from left to right, I can "move" the
pixel to the upper-left corner of each subsequent monitor.

- --
Andrew David Wong (Axon)
Community Manager, Qubes OS
https://www.qubes-os.org
-----BEGIN PGP SIGNATURE-----
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=wx6Q
-----END PGP SIGNATURE-----

[john]

i only have one display and my pixel is red (it is the pixel at (0,0) in
screen coordinates, maybe a one off error?)
btw.: i am using kde
i tried changing the wallpaper an selecting domains of different colors,
but the pixel did not change color.

-john

[Andrew]

Andrew David Wong:

> Does anyone else have a single green pixel in the upper-left corner
> of their screen? I just noticed that both of my Qubes installations
> on separate hardware have this, yet the same monitors under a
> different OS do not. It's easiest to see against a dark (e.g.,
> completely black) background.
>
> One of my Qubes machines is a workstation with three monitors. The
> green pixel starts out in the upper-left corner of the left-hand
> monitor. If I disable the monitors one-by-one, from left to right,
> I can "move" the pixel to the upper-left corner of each subsequent
> monitor.
>
>

Yep, I have it, too. Mine actually changes color from time to time.
I think it depends on the window border colors of some window one had
maximized. But I really don't know! Sometimes it doesn't appear at all.

Andrew

[Unman]

I think it is artefact of window decoration, as it does seem related to
having had title bar in that corner: I dont think necessarily maximised.
Is it interaction with KDE top left hotspot?

[Andrew]

Unman:

It happens to me while I'm using XFCE, so I don't think it has anything
in particular to do with KDE.

Andrew

[Andrew]

Andrew:

I just played with this for a little bit and noticed some interesting
behavior.

There's always an extra empty pixel row on top of the screen. If I move
the mouse cursor, I can see exactly one row of pixels which is black
except the left-corner and the outline of my cursor.

However, no matter how I try to move windows, I can't get anything into
the empty first row.

However however (:)), if I put a window into full screen mode, it *does*
occupy that row. But the left-corner pixel doesn't change color!

Andrew

[Andrew David Wong]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Yes. I've been using Qubes for years, but I never noticed it until I
tried watching a movie in fullscreen mode today. During dark scenes,
that one bright pixel is very noticeable!

- --
Andrew David Wong (Axon)
Community Manager, Qubes OS
https://www.qubes-os.org
-----BEGIN PGP SIGNATURE-----
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=QZaG
-----END PGP SIGNATURE-----

[Andrew David Wong]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Possibly useful info: On the KDE lock screen, the bright pixel isn't
visible. (At least not for me. My KDE lock screen background is just
solid black (#000).)

- --
Andrew David Wong (Axon)
Community Manager, Qubes OS
https://www.qubes-os.org
-----BEGIN PGP SIGNATURE-----
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=Ydyw
-----END PGP SIGNATURE-----

[Andrew]

Andrew David Wong:

Same for XFCE.

Andrew

[Marek Marczykowski-Górecki]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

I see it from time to time too. Guess some application creates 1x1
border-less window. AFAIR GTK uses something like this for its internal
purposes. Normally that window wouldn't be visible, but in Qubes we
enforce that window can't hide its borders completely.

You can check what creates this window by:

1. Checking which VM owns it: call xprop in dom0 and click that window -
see _QUBES_VMNAME property; if there is some hint in window title, you
can guess based on it; if not:

2. Check window properties in that VM (also using xprop, this time
called inside VM)

- --
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2

iQEcBAEBCAAGBQJXPhMqAAoJENuP0xzK19csbVYH/R1c9S4sJ61sg3kJH8INggnZ
awQfWWg5DZL6Zoz4VYIjnrhN1MPojrv3nYD9bqZgY/WUsYZ9VoiAS/Drd+GQAjID
ggrXxGSFUzVXjfWkPWBpfD8/PnMLSPOpXVGA/qVf0ksZckoMbXxsM86SSY0o3wGy
ctiz/M4ba1dB9np7d61sJJd2/UZb7nBeMMfH9wzjFIhOL5z2JjpwndvZ9WikubHv
O44vMVfLdA5d/iHvPEhNxdz4rh631Psxa0M1IE+QR5oRNM8pc95yclhX+UQMJUtR
os6YOaqwFriIthBGKDHM/rkTtLwYrMQkr4w48AYcMmuqXG8k04QxE2cs1hGjLvA=
=tdus
-----END PGP SIGNATURE-----

[Andrew]

Marek Marczykowski-Górecki:

Thanks. In my case, it's a Thunderbird window with:
> WM_NORMAL_HINTS(WM_SIZE_HINTS): program specified location: 0, 0
> program specified minimum size: 0 by 0

xprop from within the VM didn't give me much that's interesting. I
did get a window ID number but I'm not sure how to use that to get
more insight about what it's for. I'll just assume you're right that
this window just serves some GTK purpose.

It seems to me that this /is/ a bug, because /either/ all windows
should be visible, in which case a single pixel is too easy to
disguise, /or/ these kinds of windows should somehow not be visible at
all, not appear as an annoying single pixel.

Not really sure how to resolve these two conflicting ideals, but the
status quo is also annoying. So, how to proceed?

Andrew

[Marek Marczykowski-Górecki]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Window can be off screen and in fact this is the case for 1x1 window of
Thunderbird on my machine:
0x2000b11 "Thunderbird": ("Popup" "Thunderbird") 200x200+0+0 +0+0
1 child:
0x2000b12 (has no name): () 1x1+-1+-1 +-1+-1

Curious why it is on screen on your system. Any ideas? Some specific
version? Which template?

- --
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2

iQEcBAEBCAAGBQJXPhvqAAoJENuP0xzK19csuD4H/0rWwo9VyeM88r+xtfrKJVUa
4ybnNJirQH0gUb7UBOw/Rpg7pIJl6Wls+dzuWVtfRkjaXelcnbP2eBGzRqgIcIMN
EZMdFvUSToviArmV/uZt47vv4OydUhPuNGHLCjwaj51ssfL7eHUIM7tAglOK5+fA
sTIMEVv4Y3xXkZNxcj4DblfldtEHbfwp6LV+2Vy9Rj7+UjpwsdvFupCLhWSauzpd
dYRkBo9c+g5IHZ0LpxgJv62OF/qbGBYQedHYn5NOPuNrJZZSpnQa0e+tqsbuFw0V
MfrUhZMmb/yUt84HqBrgeZexny8gt56/EOhcZA4MeXpNfb4kscH2rYyKY/GEdR4=
=yZT1
-----END PGP SIGNATURE-----