[reverted for now] Fractional scaling in Fedora 40 Workstation makes some applications blurry

Problem

NOTE: This change has been deferred. Fractional scaling is currently NOT enabled in any stable Fedora version.

In GNOME in Fedora 40 Workstation, old applications (which don’t support Wayland natively) may appear blurry if you enable display scaling.

Note: GNOME might enable display scaling even automatically – that depends on what particular display you have.

Cause

Display scaling is the process of making everything (application windows, texts, etc) bigger on your screen. It’s often used for modern high-density displays, otherwise everything would be tiny and hard to read. There are two display scaling techniques - integer scaling and fractional scaling.

GNOME in Fedora 39 and older only supports integer scaling, which allows you to scale desktop content to 100%, 200% or 300%, but nothing in between. This results in a sharp image even for old applications, but the content is often either too tiny or too large.

GNOME in Fedora 40 supports fractional scaling by default, which allows you to scale desktop content to fractional sizes like 125%, 150%, etc. This allows you to better fine-tune the preferred size, but only Wayland-native apps will appear clear and sharp. Older apps running in XWayland (because they depend on X11) might seem blurry, especially their text. This happens even if you set the scale value to integer numbers, like 200% or 300%.

Related Issues

Fedora Workstation WG ticket: https://pagure.io/fedora-workstation/issue/357
Bugzilla: 2238905 – F40 workstation's Displays Scale is 125% by default on 1920x1080 14" laptop display

Workarounds

Try 100%

Check GNOME SettingsDisplays → select display → Scale. Perhaps your scale factor was automatically set by GNOME and you might actually not need it. Set 100% and see if works well for you. If you run at 100%, all apps will be clear and sharp.

Use integer scaling if acceptable

If you’re OK with just using integer scaling values like 200% or 300%, you can disable fractional scaling. You’ll lose the ability to set scaling in 25% intervals, but the old apps won’t be blurry.

First, set the display scale to 200% or 300%, as preferred. Then disable fractional scaling using this command in your Terminal:

gsettings set org.gnome.mutter experimental-features "[]"

And finally log out and log back in. In GNOME Settings, you should now only see integer scaling options, and old apps shouldn’t be blurry.

If you ever change your mind, you can re-enable fractional scaling by running this command in your Terminal:

gsettings reset org.gnome.mutter experimental-features

and logging out and back in again.

Tweak some of the old apps

If you want to use fractional scaling (non-integer values), but blurriness of some apps bother you, explore whether those apps can be switched to a native Wayland rendering. (Be aware that some issues might arise if you no longer run them in their default configuration).

Firefox - Supports Wayland out of the box, if you install it from Fedora repositories (recommended). Its Flathub version doesn’t enable Wayland by default yet, but you can change it.

Chromium-based browsers (Chrome, Edge, etc) - Don’t support Wayland out of the box, but you can change it.

Anything else - Search the web with the keywords of the app name, Wayland, fractional scaling. Perhaps you find a solution. Also please ask the app vendor to implement a native Wayland support.

2 Likes

I afraid that all to blow off this problem. Now I have to change scaling to 100% every time when I start X11 app. If woudn’t do it then 4K resolution is not available. Available only FHD resolution if 200% scaling is selected in gnome settings.

That makes sense because 200% scaling on FHD is actually equivalent in pixels to what a 4k screen is capable of displaying 1920x2=3840, 1080x2=2160 : 3840x2160 is 4k resolution.

@mikhail Do you mean games? Because that’s another side effect of using fractional scaling - X11 apps don’t have access to all system resolutions (at least from what I’ve read). That would probably deserve a separate Common Issue entry, I guess.

The fractional scaling support was deferred to Fedora 40. I’ll keep this issue as Proposed, so that we can update it and use it in the F40 cycle.

If you’ve enabled non-integer display scaling (125%, 150%, etc) and after the latest update (when it got disabled) you see a distorted font rendering, read:

2 Likes