With KDE (and perhaps some other desktop environments) there are two independent, different resolution values that affect how the GUI is scaled. The first value is reported by "xdpyinfo | egrep -i resolution" and depends on the actual screen size (at least if the X server can determine it). In my case it returns resolution: 209x209 dots per inch The second value is reported by "xrdb -query | egrep -i 'xft' and can be overwritten by KDE's "force font dpi option". In my case it results in Xft.dpi: 120 Xft.hinting: -1 Xft.rgba: none The "force font dpi option" is very often necessary to work around problems in some application that do strange GUI scaling for very high DPI values (firefox is a prime example). Anyway, LibreOffice looks totally right on my screen with these settings but there is a minor drawback. If I set the zoom to "100%" a DIN-A4 page does not has the size of an actual DIN-A4 page but is too small. If I set 175% the DIN-A4 has the correct size. Nothing of this is very surprising, because 209/120 = 1.74. However, it would be nive, if LibreOffice would proceed as follows: (1) For GUI styling (menu bars, dialogs, etc.) use the resolution as being reported by xrdb. (This is already the case.) (2) But use the resolution as reported by xdpyinfo to scale/zoom the actual page content.
Sounds reasonable -> NEW
This is still an issue on Linux and on Wayland, with LibreOffice 24.8.0.3 Also I changed the Importance to "normal" rather than "enhancement" since the LibreOffice user manual states 100% zoom should display images at actual size. I know this is possible on Linux/Wayland – Krita has a good system where you can switch the zoom setting between Print Size and Pixel Size. On KDE Plasma there is currently a bug where if the Global Scaling is different on different attached monitors the scaling within applications won't be correct, but with a single monitor, or with the same scaling on both monitors, Krita is able to correctly display an A4 sized document at A4 size even while using fractional Global Scaling in KDE Plasma. Fixing this would be great, but I would actually recommend implementing a similar solution to Krita. Instead of "Pixel Size", I think "UI Size" would be a more appropriate second zoom option for LibreOffice, and describes the current behaviour on Linux ("Pixel Size" in Krita means 100% zoom displays an image dot to dot accurate, while 100% zoom in LibreOffice assumes an arbitrary size which is then affected by global scaling options). These two options – "UI Size" and "Print Size" – would allow the user to either zoom a document relative to their UI and other apps, or to zoom relative to the physical size of the document. Why keep current behaviour as an option? If you use a TV as a monitor to reduce eye strain, zooming by actual size is nonsense, especially if you are using it as a second monitor. A document at 100% zoom on your close monitor will look tiny on your distant monitor. This is an extreme example, a more common one being a laptop with a small screen and small, compact scaling settings, that is frequently docked and used with a larger monitor. This is my use case and for that it is useful to have documents display at a smaller physical size on my small screen along with the rest of my smaller UI. But the option to view at actual size is still important.