Bug 482539 - top panel on one screen limits vertical space on secondary screen
Summary: top panel on one screen limits vertical space on secondary screen
Status: RESOLVED FIXED
Alias: None
Product: kwin
Classification: Plasma
Component: multi-screen (show other bugs)
Version: 6.0.0
Platform: Gentoo Packages Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords: multiscreen
: 451979 (view as bug list)
Depends on:
Blocks:
 
Reported: 2024-03-06 13:13 UTC by Martin Bednar
Modified: 2024-03-08 22:15 UTC (History)
3 users (show)

See Also:
Latest Commit:
Version Fixed In:


Attachments
Screenshot showcasing the issue. Note the wallpaper on top of left screen above maximized firefox. (1.32 MB, image/png)
2024-03-06 13:13 UTC, Martin Bednar
Details
Screen configuration (1.35 MB, image/png)
2024-03-06 16:45 UTC, Martin Bednar
Details
kscreen-doctor output (3.10 KB, text/plain)
2024-03-06 16:48 UTC, Martin Bednar
Details

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Description Martin Bednar 2024-03-06 13:13:55 UTC
Created attachment 166477 [details]
Screenshot showcasing the issue. Note the wallpaper on top of left screen above maximized firefox.

Setup: Two 4K screens side by side. Wayland. Primary screen has a topside menubar panel. Secondary doesn't have any top panel.

Fullscreen windows on secondary screen don't maximize vertically, they leave a vertical space the size of the primary screen's menubar panel. 

Note: this is not a regression. 
Note2: Sometimes there is a line of randomly colored pixels (as if uninitialized) on the absolute right of the primary screen. Possibly irrelevant.

KDE Plasma Version: 6.0.0
KDE Frameworks Version:  6.0.0
Qt Version:  6.6.2
Comment 1 fanzhuyifan 2024-03-06 15:50:31 UTC
Do you have fractional scaling enabled? Is this on x11 or wayland?

See also BUG 477791
Comment 2 Martin Bednar 2024-03-06 16:45:15 UTC
Created attachment 166487 [details]
Screen configuration

Removing the panel on primary screen allows complete fullscreen on secondary screen. 
Such a panel on the secondary screen does not result in this behaviour on primary screen.
Not related to the panel being at the top: resizing a bottom panel on primary screen results in snapping to size of primary screen panel.

Attached screen configuration KCM screenshot.  Screenshot also showcases the "drag to top to maximize" overlay showing the how the window would get maximized.
Setting scaling to 100% (didn't preform logout/login) didn't change the behaviour.

Definitely sounds similar to "screens sharing one pixel on edge", which is why I mentioned the sometimes visible "uninitialized" pixel column.
This pixel column is on the right side, and is visible when fullscreen smplayer is active. Its existence is dependent on the selected scaling.
Comment 3 Martin Bednar 2024-03-06 16:46:21 UTC
Forgot to answer: wayland.
Comment 4 fanzhuyifan 2024-03-06 16:46:59 UTC
Thanks! Could you also provide the output of `kscreen-doctor -o`?
Comment 5 Martin Bednar 2024-03-06 16:48:33 UTC
Created attachment 166488 [details]
kscreen-doctor output
Comment 6 Martin Bednar 2024-03-07 09:55:09 UTC
https://bugs.kde.org/show_bug.cgi?id=451979 Looks very similar.
Comment 7 fanzhuyifan 2024-03-07 17:09:43 UTC
(In reply to Martin Bednar from comment #6)
> https://bugs.kde.org/show_bug.cgi?id=451979 Looks very similar.

That was before https://invent.kde.org/plasma/kscreen/-/commit/cff5739c872393bfbfe9bca43a5763f4d9ec3e6e and probably fixed by that. I am marking that as a duplicate of this since the root cause should be the same, if that hasn't been fixed already.

I can't reproduce both on my end with two displays and fractional scales. But I don't have two 4k screens as described in your setup.
Comment 8 fanzhuyifan 2024-03-07 17:09:54 UTC
*** Bug 451979 has been marked as a duplicate of this bug. ***
Comment 9 Martin Bednar 2024-03-07 17:16:18 UTC
I'm open to allowing you remote access (over krfb? ) . If interested, send me an email directly please.
Comment 10 fanzhuyifan 2024-03-07 17:27:03 UTC
> Geometry: 2194,0 2195x1235

The x coordinate of the right screen is at 2194 instead of 2195, so there is one pixel of overlap. This might be a left-over thing from previously stored screen configurations. Does this problem disappear if you go to system settings - display configurations, drag the monitors a bit, and drag them back?
Comment 11 Martin Bednar 2024-03-07 17:31:47 UTC
Damn... It indeed did disappear.
Comment 12 fanzhuyifan 2024-03-07 17:35:22 UTC
(In reply to Martin Bednar from comment #11)
> Damn... It indeed did disappear.

So I suspect the issue is that we are not updating the display configuration from before the fix (https://invent.kde.org/plasma/kscreen/-/commit/cff5739c872393bfbfe9bca43a5763f4d9ec3e6e) to after the fix.
Comment 13 Martin Bednar 2024-03-07 17:36:31 UTC
yes, I haven't changed that config in more than half a year.
Comment 14 Nate Graham 2024-03-08 22:15:09 UTC
Yeah, I don't believe there was any migration code. So the issue is now worked around, but existing setups might be affected. Probably still worth fixing, if it can be done without too much pain.

Let's get a new bug report to track that, though.