Dear list,

I believe, there is either a bug in X11 or KDE (plasma).

Following problem, do the following:

- Start any browser like firefox or similar
- go to youtube or soemwhere else and start a video
- switch the video to fullscreen
- now switch back, close the video
- you will now see the browser too big for the screen (have to close with ALT+F4)

I believe, this behaviour is caused as my screen resolution is not 16:10 as most screens are, but 16:9 (it is a laptop DELL Latitude 5400).

Sadly my other external monitor oin my desktop computer is also 16:9, so I can not test it.

This issue appeared first after upgrade to trixie.

Last but not least: In wayland I could not not test it, because in wayland the behaviour of windows is completely other. Also: I do not want to use wayland, as it is not as fast and stable as X11 on this computer.

IMHO this is a bug either in X11 or the window manager, which should be filed. But I m not sure, which is responsible for this behaviour.

Best regards

Hans

P.S. If I am the only person with this issue, you need not to care. I can live with this.

--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Hans composed on 2026-01-09 15:49 (UTC+0100):

I believe, there is either a bug in X11 or KDE (plasma).

Following problem, do the following:

- Start any browser like firefox or similar
- go to youtube or soemwhere else and start a video
- switch the video to fullscreen
- now switch back, close the video
- you will now see the browser too big for the screen (have to close with ALT+F4)

I believe, this behaviour is caused as my screen resolution is not 16:10 as most screens are, but 16:9 (it is a laptop DELL Latitude 5400).

I can't help with much specific to Plasma, but there are things to try. First, with browser still having focus, hit F11, the fullscreen toggle key in most browsers - once or twice. If that doesn't work, try a switch to vtty after closing
the video (e.g. Ctrl-Alt-F[3,4,5] to get to vtty, then Alt-F[2,7,1] to return to
Plasma, whichever numbers work; not all configurations run (SD-)DM on the same vtty, with 1 or 2 recently more common in place of the traditional 7. If that doesn't help, run xrandr in Konsole to discover the name of your video output connection, likely HDMI-1, or DVI0, or DisplayPort-1 or similar. Then use that to
run xrandr again to reset the display e.g. thus: xrandr --output HDMI-1 --auto. Last resort, try Plasma systemsettings for display, and apply a resolution change,
then change it back.

Also, 16:9 is an HDTV standard since roughly 3 decades ago, thus very common in computing, probably much more common than 16:10, which AFAICT only arose for computing environments many years after HDTV was established. Display panels back
then in 16:9 were readily available and adapted for use for computer displays, with 16:10 initially common in 1280x800 for early widescreen laptops. These two aspect ratios tend to be more common in certain sizes, with 24" one of few sizes
common to both ratios. e.g. 19", 21" and 27" I've only seen in 16:9 (both 1920x1080 and 1600x900), while 22" (1680x1050) I've seen mostly, & 30" (2560x1600)
I've seen only, in 16:10.
--
Evolution as taught in public schools is, like religion,
based on faith, not based on science.

Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata

--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Hans wrote:

I believe, there is either a bug in X11 or KDE (plasma).

Following problem, do the following:

- Start any browser like firefox or similar
- go to youtube or soemwhere else and start a video
- switch the video to fullscreen
- now switch back, close the video
- you will now see the browser too big for the screen (have to close with ALT+F4)

I believe, this behaviour is caused as my screen resolution is not 16:10 as most screens are, but 16:9 (it is a laptop DELL Latitude 5400).

16:9 is, by far, the most widely used aspect ratio. 16:10 is the
next most widely used.

I have both available here, and I do not see the problem you are
having.

I use trixie, X11, and XFCE, so perhaps this is a KDE bug.

-dsr-

--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

I'm seeing similar behavior with Firefox 146.0.1 on Sid with FVWM.
Hitting escape restores the window size but leaves the browser too large
for the window and the active areas of all buttons offset below the
button image. Moving any margin of the window restores normal behavior.
At a guess, Firefox is not repainting the window.
--
John Hasler
john@sugarbit.com
Elmwood, WI USA

--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

I rechecked again.

I believe, it is a KDE issue. Using F-11 (maximize) then F11 again does not fit
back to the correct window size.

Also switching to any console (CTL+ALT+F2) and back to Alt+F7 does not do have any effect to the size.

So, I will file a bug to the plasma maintainers. Hope, they will help.

Best

Hans

--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Dan Ritter <dsr@randomstring.org> writes:

16:9 is, by far, the most widely used aspect ratio. 16:10 is the
next most widely used.

I thought 16:10 is pretty much dead, except in monitors from the decade
before last. Although surprisingly, my newish Thinkpad T16 has a 16:10
panel. But that seems like an exception among the 16:9 hordes.

--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Perhaps either alt-space Unmaximize followed by alt-space maXimize would work, or even alt+button_3 to resize the window to usability would work.

My bugreport was not for getting a workaround!! I can handle this for myself.

This was for the maintainer to get him fixed it (if he cares).

Hans



--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Mon, 19 Jan 2026 17:07:17 +0100
Hans <hans.ullrich@mail.de> wrote:

My bugreport was not for getting a workaround!! I can handle this for
myself.

This was for the maintainer to get him fixed it (if he cares).

Ah, well, that's different. Not all maintainers are on this list. The
preferred way to file a bug report is to file a bug report at
bugs.debian.org.



--
Does anybody read signatures any more?

https://charlescurley.com
https://charlescurley.com/blog/

--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Ah, well, that's different. Not all maintainers are on this list. The preferred way to file a bug report is to file a bug report at bugs.debian.org.

I already did this. Tests revealed, that it is a problem with KDE, especially with kwin. So I filed a bug to it.

I suppose, it is related to my screen resolution, which is 16:9, as it seems, the window in full screen wants to switch to 16:10 (so it is too big).

However, I can not prove this, as all my monitors are 16:9. None is 16:10 (native).

So, also I doubt, the KDE maintainers will fix this (as the packages are too old in debian/stable), kit might be, this bug is also in latest KDE packages.

Maybe then they will fix it, we will see, if (in case of fiunding this big), it
will also been fixed in downstream packages.

As far as I experienced, I suppose, they will not. There was already feedback by some maintainer telling "we fix only on latest versions".

Such I doubt it will be fixed, but all in one it was important to me, to mention it at all. So I am sure, they are aware of this.

Long fpor short: We have now to wait, what will happen.

Let us hope the best.

Hans

--- PyGate Linux v1.5.2
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)