`ISO_Level5_Shift` not recognized by Firefox/Gecko Flatpaks on GNOME Shell 48.3 (Wayland), but works on Vanilla OS 2

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1

On Fedora Silverblue, when using GNOME Shell 48.3, ISO_Level5_Shift (mapped to Right Alt) does not function within Firefox-based Flatpak applications (Zen Browser, official Firefox Flatpak).

  • The browser registers no input on most keys pressed while Right Alt is held. The only exceptions I’ve found so far are F6 and Return which get through unmodified (as intended). In contrast F5 and Backspace do not register when Right Alt is held. None of these keys are 5-layer keys.

  • However, this exact setup (same ISO_Level5_Shift mapping, same Zen Browser Flatpak version) works perfectly on a machine running Vanilla OS 2 with GNOME Shell 48.1. I used dconf to dump all settings from the working machine and load them onto the problematic machine. Even afterwards one difference I noticed was that in the Settings app under Keyboard > Special Character Entry the working machine read “Default” while the problematic machine read “Right Alt”. I tried changing that to “Left Alt” and “Right Control” with no difference in behavior. “Default” was not an option.

  • ISO_Level5_Shift functions correctly in other Flatpak applications (e.g., GNOME Maps, Steam) and native applications (Kitty) on the Fedora Silverblue machine running GNOME Shell 48.3.

  • wev output on the problematic Fedora Silverblue (GNOME Shell 48.3) machine shows ISO_Level5_Shift events being generated when Right Alt is pressed, along with the correct level 5 characters for subsequent keys.

  • ISO_Level3_Shift mapped to to Left Alt works.

  • I couldn’t rule out that it’s a regression in GNOME. I tried repeatedly to downgrade Silverblue to Fedora 41 but it always failed.

  • The identical flatpak info output for Zen browser on both machines meaning it can’t just be Firefox:

          ID: app.zen_browser.zen
         Ref: app/app.zen_browser.zen/x86_64/stable
        Arch: x86_64
      Branch: stable
     Version: 1.14.8b
     License: MPL-2.0
      Origin: flathub
  Collection: org.flathub.Stable
Installation: system
   Installed: 344.9 MB
     Runtime: org.freedesktop.Platform/x86_64/24.08
         Sdk: org.freedesktop.Sdk/x86_64/24.08

      Commit: ea8e578e06f8d639b27bfde98f7248c38d5d526fd0e66bb57d133c2b944b1357
      Parent: 54de73e2b4758138923d08dcd4586cbf13ccd123e8209c24f705faf188df16ab
     Subject: Merge pull request #78 from flathub/update-to-1.14.8b (e9c5c4d97823)
        Date: 2025-07-26 18:00:38 +0000
         Sdk: org.freedesktop.Sdk/x86_64/24.08
3

See this Firefox bug.

2 Likes
4

Interesting, but I’m skeptical since this works on an identical browser flatpak on another wayland GNOME desktop. And I’ve just found another flatpak where the same thing happens: Emacs :face_with_spiral_eyes:

5

I just tried reproducing this on fedora live workstation 42 and couldn’t. It seems to be unique to the atomic variant.