The 'clone' mode with an external monitor is basically unusable with a 4k laptop *** NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols. See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports *** STEPS TO REPRODUCE 1. Use a 4k laptop (with 200% scaling) connected to an external <FHD video projector or monitor 2. Try to set the display configuration in 'clone' mode OBSERVED RESULT 1st problem: the laptop display UI is completely messed, since the resolution is set to FHD but still with the 200% scaling 2nd problem: nothing appears on the external video projector or monitor 3rd problem: even if you disconnect the external video projector, the laptop still keeps its low resolution, does not come back to the native 4k resolution 4th problem: in KDE display settings, it is impossible to set back the resolution to 4k, the resolution does not exist anymore 5th problem: even if you manage to change the resolution, it is impossible to apply the change since the bottom part of the setting window with the 'apply' button is hidden and there is not way to scroll down EXPECTED RESULT SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: Debian Bookworm (available in About System) KDE Plasma Version: 5.23.5 KDE Frameworks Version: Qt Version: ADDITIONAL INFORMATION
I'm afraid it doesn't work to report multiple bugs in a single bugzilla ticket. We'll never get anywhere this way. Can you open multiple Bugzilla tickets, one per issue? See https://community.kde.org/Get_Involved/Issue_Reporting#One_issue_per_Bugzilla_ticket In these separate bug reports, please add information about the versions of KDE and Qt software you're using, and mention whether you're using the X11 session or the Plasma session. Finally, please mention if you have manually set the PLASMA_USE_QT_SCALING=1 environment variable, or not. Thanks!
> I'm afraid it doesn't work to report multiple bugs in a single bugzilla ticket. We'll never get anywhere this way. Can you open multiple Bugzilla tickets, one per issue? See https://community.kde.org/Get_Involved/Issue_Reporting#One_issue_per_Bugzilla_ticket Yes, sorry for my bad behavior, I knew that but was in a hurry. I will try to report separately. My hope was that a KDE dev would test this setting: 4k laptop with X11/200% scaling, <FHD external monitor, clone mode. > In these separate bug reports, please add information about the versions of KDE and Qt software you're using, and mention whether you're using the X11 session or the Plasma session. Finally, please mention if you have manually set the PLASMA_USE_QT_SCALING=1 environment variable, or not. Sorry I meant to report that. This is with X11. KDE version tested was 5.23.5. I will test with 5.24.3 tomorrow. I have not set manually PLASMA_USE_QT_SCALING.
I have that exact setup and can confirm that it works very poorly. This is a known issue with X11 that is essentially impossible to fix, unfortunately. The only real solution is to use the Wayland session, where mixed-DPI multimonitor setups work much much better. Can you try it out and see how it works for you?
> I have that exact setup and can confirm that it works very poorly. Good to know you have that setup, this way problem will be fixed more quickly! :-) > This is a known issue with X11 that is essentially impossible to fix, unfortunately. I know that on X11, the scaling is only global and not per-monitor. But still, there are not so many problems on X11/Gnome. On KDE, basically, when you try the clone mode with this setup, it messes up your display settings and the only way I found to come back to the normal state is to exit the Plasma session. > The only real solution is to use the Wayland session, where mixed-DPI multimonitor setups work much much better. Can you try it out and see how it works for you? OK, I will try the Wayland session tomorrow as well. Thanks Nate.
So I tested again the problem today with X11 and 5.24.3, and things work much better now. I don't know if this is the update to 5.24.3 or the fact that I restarted the plasma session. Now, I can come back to the 4k resolution once the external monitor is connected, so I think the main issue is gone. The only minor problem I see is that the resolution does not come back automatically to 4k, it stays in FHD, and you have to go to the display settings and manually change the resolution. So I changed the title accordingly. On Wayland, things work much better, since both display have their own resolution which are not affected by the clone mode. One issue I remarked with Wayland though is that the presentation mode of LibreOffice does not appear on the external display, but that is for another bug report...
Yeah, that's https://bugs.documentfoundation.org/show_bug.cgi?id=137924.
The LibreOffice bug you reported to has apparently nothing to do with the presentation mode of Impress. I reported the wayland LibreOffice presentation problem here: https://bugs.kde.org/show_bug.cgi?id=451852 Not sure if this bug belongs to kwin or to LibreOffice, though.