Fontforge not starting at all in a KDE Plasma wayland session

[callegar]

Trying to use fontforge on Manjaro linux, with a KDE plasma session on Wayland.

Fontforge cannot be started.

Copyright (c) 2000-2023. See AUTHORS for Contributors.
 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
 with many parts BSD <http://fontforge.org/license.html>. Please read LICENSE.
 Version: 20230101
 Based on sources from 2023-04-07 06:26 UTC-ML-D-GDK3.

(fontforge:37290): Gdk-WARNING **: 18:12:56.283: cannot open display:

The output above also reports the fontforge version.

Using an X11 Plasma session, fontforge starts normally. Unclear why it is not using XWayland on Wayland.

When reporting a bug/issue:

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• The FontForge version and the operating system you're using
• The behavior you expect to see, and the actual behavior
• [ X Steps to reproduce the behavior
• (optional) Possible solution/fix/workaround

[callegar]

Diagnosed: you need to unset GDK_BACKEND or set it to x11 for fontforge to work.
If fontforge cannot deal with GDK_BACKEND=wayland probably it should ignore it rather than breaking.

[iorsh]

How do gimp or inkscape start at the same command prompt? I'm not sure whether applications or the window manager are in charge of GDK_BACKEND setting.

[callegar]

Gimp and inkscape start just fine with GDK_BACKEND set to wayland on my system. Xeyes suggests that gimp starts as an X11 application, while inkscape is wayland.

[C0rn3j]

Can confirm that the var breaks things.

I did not run into the problem though as I do not force set GDK_BACKEND, just randomly found this issue.

@callegar On kwin you can use kwin debug console to see what is X and what's Wayland.
Your xeyes test was correct though.

Operating System: Arch Linux 
KDE Plasma Version: 6.0.2
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2
Kernel Version: 6.8.1-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 7600X 6-Core Processor
Memory: 62.0 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 4090/PCIe/SSE2
Manufacturer: Gigabyte Technology Co., Ltd.
Product Name: X670 AORUS ELITE AX