[Bug 50717] New: Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

Bug ID: 50717
           Summary: Wine places 1x1 pixel window on top of fullscreen
                    window, blocking direct scanout on Wayland
           Product: Wine-staging
           Version: 6.2
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
                CC: [e-mail], [e-mail]
      Distribution: ---

KWin developer Xaver Hugl found this while investigating the cause of direct
scanout getting blocked with Wine fullscreen windows on Wayland:
"Wine puts a 1x1 pixel big override-redirect window on top of the fullscreen
window that stops direct scanout. I'll add a workaround for now but at first
glance looks like a Wine bug to me."
https://invent.kde.org/plasma/kwin/-/merge_requests/718#note_191539

"I verified that it isn't caused by Xwayland / happens on a normal X session as
well"
https://invent.kde.org/plasma/kwin/-/merge_requests/728#note_191637
(this MR also contains the workaround, and indeed it makes direct scanout work
with Wine)

As a result, performance of fullscreen 3D Wine applications on Kwin Wayland
git-master is negatively affected, as unnecessary compositing affects frame
presentation and causes lots of dropped frames under high GPU load.
It is well possible that this also negatively affects Gnome and Sway Wayland,
but also Gnome unredirecting on Xorg.

-staging and Proton are affected, might also apply to regular wine. It doesn't
matter if WineD3D or DXVK is used (as this probably is very specific to Wine's
window management and not the 3D API).

It looks like if the proper fix was if Wine wouldn't spawn the 1x1 pixel window
on top anymore.

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

Bednar  changed:

What    |Removed                     |Added
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                 CC|                            |[e-mail]
                   |                            |m

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

--- Comment #1 from Zebediah Figura  ---
Can you please test with upstream (non-staging) wine first?

It also may very well be that the program itself is creating this window, not
Wine. What application is this?

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

--- Comment #2 from [e-mail] ---
Created attachment 69577
  --> https://bugs.winehq.org/attachment.cgi?id=69577
1x1px unmanaged window

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

--- Comment #3 from [e-mail] ---
I've confirmed the issue with regular wine 6.2 with a clean prefix: Start
Windows version of Unigine Valley with D3D11 -> WineD3D. The launcher doesn't
trigger the 1x1px unmanaged window, but as soon as you start the actual program
with 3D rendering, the 1x1px unmanaged window occurs. It apparently occurs with
any 3D game in Wine.

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

Zebediah Figura  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
            Product|Wine-staging                |Wine
          Component|-unknown                    |-unknown
                 CC|[e-mail] |
                   |, [e-mail]      |

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

Rémi Bernon  changed:

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                 CC|                            |[e-mail]

--- Comment #4 from Rémi Bernon  ---
It's most probably the "dummy parent" window used to reparent stale client
windows.

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

--- Comment #5 from Rémi Bernon  ---
Created attachment 69709
  --> https://bugs.winehq.org/attachment.cgi?id=69709
Possible fix

Is something like that helping in any way?

Instead of creating an override-redirect window, which will bypass the window
manager and possibly stay on top of all windows, it uses EWMH desktop window
type / below all state to try to hide the dummy parent as much as possible
without bypassing the window manager.

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

--- Comment #6 from [e-mail] ---
I can confirm that your patch prevents the unmanaged window to spawn.

It turned out that also Wine's system tray icon feature can be problematic
(e.g. Battle.Net client), as it (independently of the desktop environment?)
spawns a 100% translucent window with on-top property. Is it really necessary
that it is always on top? This can make it placed on top of fullscreen windows
and thus can/does prevent direct scanout as well. As a result, an exception for
100% translucent windows was added to kwin's direct scanout feature, but this
is probably better also fixed at the root?

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

François Gouget  changed:

What    |Removed                     |Added
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                 CC|                            |[e-mail]
           Keywords|                            |patch

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

Alex Folland  changed:

What    |Removed                     |Added
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                 CC|                            |[e-mail]

--- Comment #7 from Alex Folland  ---
Is Rémi's patch in comment 5 still applicable?  If so, is there a chance of
having it applied to upstream wine any time soon?  If so, this fix sounds like
it would be better to get in to wine 7.0 than not.  This is just my opinion. 
Thanks for the patch, Rémi!

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

--- Comment #8 from Rémi Bernon  ---
Well I'm not completely sure the patch is not going to cause any regression, as
it will change the way the dummy parent window is created.

I'm expect that if the window manager reports STATE_BELOW and
WINDOW_TYPE_DESKTOP support it's hopefully going to work fine, but who knows
that WM can do with it...

As the comment above suggests it also looks like it's not the only problem and
I don't have anything for the systray.

[Bug 50717] Wine places 1x1 pixel window on top of fullscreen window, blocking direct scanout on Wayland

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=50717

--- Comment #9 from Alex Folland  ---
That full-screen translucent window issue sounds like it may be an issue for
another issue report, and therefore may be fixable independently of the issue
this report specifies.  Does that sound right, or is this issue meant to
capture all ways that wine can prevent Wayland direct scanout?