Created attachment 181143 [details] Transparent Horizontal Lines in Kwrite SUMMARY STEPS TO REPRODUCE 1. fractional scaling at 115% 2. open Kwrite OBSERVED RESULT Horizontal transparent lines appear within the editor area. EXPECTED RESULT Normal KWrite Window SOFTWARE/OS VERSIONS Linux/KDE Plasma: Linux 6.14.5 KDE Plasma Version: KDE Plasma 6.3.5 wayland KDE Frameworks Version: 6.13.0 Qt Version: 6.9.0
Does that happen for some 125% scaling, too? Not sure if that will ever be fixed, with non 1/(2^x) scalings there will be always rounding errors.
(In reply to Christoph Cullmann from comment #1) > Does that happen for some 125% scaling, too? Not sure if that will ever be > fixed, with non 1/(2^x) scalings there will be always rounding errors. No it only appears with 115% scaling.
Could we just not allow scaling that is not even representable as a proper floating point number? For X11 we only allow increments in 1/16 steps or something like that, 0.1 or 0.5 steps just lead to rounding issues everywhere, that is not fixable on the app level.
Not a KScreen bug; almost certainly something in KWrite or KTextEditor. If not that, *maybe* it's a KWin thing. CCing some KWin devs for more info.
I only know that with strange scaling factors you might end up with rounding issues. If someone has time to search that in our code, that is welcome, I will not do that. I would recommend to use a better scaling factor as workaround, like the mentioned 1.25 that seems to help. Perhaps you can try one more close to 1.15, like 1.125, that might work, too.
(In reply to Christoph Cullmann from comment #5) > I only know that with strange scaling factors you might end up with rounding > issues. If someone has time to search that in our code, that is welcome, I > will not do that. I would recommend to use a better scaling factor as > workaround, like the mentioned 1.25 that seems to help. > Perhaps you can try one more close to 1.15, like 1.125, that might work, too. I hit this issue today and tried different scaling factors. It only happens with 1.15 scale. Not 1.00, not 1.05, not 1.10, not 1.20, not 1.25, not 1.125. The lines always stay at the same horizontal place, they do not move when scrolling.
Also happens in kDevelop and Kile. So think it's the text editor component they all share.
*** Bug 505546 has been marked as a duplicate of this bug. ***
I can reproduce this on an EndeavourOS VM with Plasma 6.4.0, Kate 25.04.2.
I can still reproduce this on fedora 42. Plasma 6.4.
*** Bug 507111 has been marked as a duplicate of this bug. ***
There is nothing we can do here, I tried to debug this in icon border code, but everything is as expected. Feel free to report this to Qt etc.
I still think that all stuff that is not some sane floating point number will lead to random rounding issues after some additions/multiplications :) But I got ignored in the past and only on X11 we tried to enforce sane zooming step in 1/16 or similar 1/2^x steps.