1325854 - With HWA enabled, when scrolling through the (large) description of a lightning task, artifacts occur (partially grey background)

Status: RESOLVED WORKSFORME

(Thunderbird :: Untriaged, defect)

Description

[Alain Knaff]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0
Build ID: 20161213204132

Steps to reproduce:

1. Create a task (todo item) in lightning, with a large description (large enough not to fit on a single page
2. After having enterer the text save and close the window
3. Re-open an edit window (as if to further edit the description)
4. Scroll through the description in the edit window


Actual results:

The background behind where text is/was turns grey, and stays white where no text was. In a way, text leaves grey traces on background
This stays like that until the mouse leaves the window.
Problem also stops after clicking into text area (and then doesn't reappear until clicking elsewhere in the edit view)
When fiddling too much with this, thunderbird eventually crashes.



Expected results:

The background should stay white.
It should not crash

Comment 1

[Alain Knaff]

Actually, the workaround to click into text does not always work.

Comment 2

[Alain Knaff]

The workaround of clicking into description text _does_ work when tried on a recently started thunderbird. However, if thunderbird has been running for a while it no longer works...

Comment 3

[Alain Knaff]

Problem does not happen when graphics acceleration is switched off or limited to blt (by setting one of the options below in /usr/share/X11/xorg.conf.d/99-intel.conf):

Section "Device"
        Identifier "intel"
#       Option "ShadowFB" "off"
#       Option "NoDRI"
#       Option "NoAccel"
#       Option "AccelMethod" "UXA" # Still shows bug in thunderbird
        Option "AccelMethod" "blt" # Works ok in thunderbird, but not firefox
#       Option "AccelMethod" "SNA" # Still shows bug in thunderbird
EndSection

Comment 4

[Jorg K (CEST = GMT+2)]

Yes, when you see graphic problems, it's always a good idea to switch hardware acceleration off. That can also be done in Thunderbird.

The rendering engine used in Thunderbird comes from Mozilla core software also used in Firefox. Can you produce similar artefacts in Firefox?

Comment 5

[Alain Knaff]

(In reply to Jorg K (GMT+1) from comment #4)
> Yes, when you see graphic problems, it's always a good idea to switch
> hardware acceleration off. That can also be done in Thunderbird.

Except, it _was_ already off in thunderbird ("Use hardware acceleration when available"= in advanced was already unchecked...) Or could it be that for some reason this setting only applies to thunderbird's core, and not to the lightning extension?

> 
> The rendering engine used in Thunderbird comes from Mozilla core software
> also used in Firefox. Can you produce similar artefacts in Firefox?

Yes, see bug #1325867 in Firefox.

It may however not be the exact root cause, as Thunderbird's variant is cured by AccelMethod blt, whereas Firefox really needs NoAccel

Likewise, I had already layers.acceleration.disabled=true within firefox, but that alone didn't help.

The fact that the internal acceleration switches are ignored is one reason why I report those bugs here, rather than to Xorg...

Comment 6

[Jorg K (CEST = GMT+2)]

Everything you see in any Gecko-based application is rendered by Mozilla core software. The TB developers really know very little about that, but there's a group of programmers in Mozilla who know this stuff.

I'm pretty sure you could see the Lightning problem also in Firefox when using the correct test data.

Anyway, on the TB side we won't/can't take any action here. I'll wait until a Lightning guy confirms this, then I'll dupe this onto bug 1325867 you mentioned. You could mention there that in TB/Lightning you get a similar effect curable by another setting.

Comment 7

[Wayne Mery (:wsmwk)]

We also have meta bug 1195947 for tracking these issues. And there may be a potential match there for thish bug.

We don't pay much attention to it for reasons jorgk has stated, plus it's not enabled by default because historically it causes more problems than it is worth.

Comment 8

[[:MakeMyDay]]

In general, there's little to add to the above comments from Lightning perspective, except you can check whether this is also an issue with all TB addons but Lightning disabled and making sure you got TB and Lightning from the same origin (e.g. both from Mozilla website or your distribution's packages).

Comment 9

[Wayne Mery (:wsmwk)]

I mention in bug 1325867 that it would be helpful to know if this reproduces in version 50.  Thunderbird beta is currently verison 50, which you can get from http://www.mozilla.org/en-US/thunderbird/channel/

Comment 10

[Alain Knaff]

In the meantime, I found the real reason: a broken GTK2 "oxygen" Engine. After switching to qtcurve, the issue disappeared, even with HWA on again.

Comment 11

[Alain Knaff]

(empty comment just to clear the needinfo request on this resolved issue. Please disregard)

Comment 12

[Alain Knaff]

(empty comment just to clear the needinfo request on this resolved issue. Please disregard)