As a workaround you can use https://github.com/Supreeeme/extest to make Onboard work. Compile it as a 64 bit library and launch onboard with
env LD_PRELOAD=/usr/lib64/libextest.so onboard
If you want to use it with KDE you can add
X-KDE-Wayland-VirtualKeyboard=true
to its desktop-file.
I used k...
This is too great not to share. Wayland devs hate this trick! I'll copy what I did from the bug report.
As a workaround you can use https://github.com/Supreeeme/extest to make Onboard work. Compile it as a 64 bit library and launch onboard with
env LD_PRELOAD=/usr/lib64/libextest.so onboard
If you want to use it with KDE you can add
X-KDE-Wayland-VirtualKeyboard=true
to its desktop-file.
I used kwin rules to get rid of window decorations and have it always on top without stealing focus. If someone knows how to make all other windows smaller when it's active that would be great.
Only problem remaining is that sometimes the keys get stuck on touch input. At least on my Steam Deck on OpenSUSE.
Edit: Just noticed that it doesn't work on KDE's lock screen. Hopefully I can find a workaround for that as well.
Edit 2: Was easier than I thought. Just select Maliit as a virtual keyboard and start Onboard manually. If you tap with your finger in a text field Maliit will come up. When you click in a text field Onboard will open. But Maliit also works on the lock screen.
And how is it able to inject key events with extest? Does it use some wayland feature to get permission to do so, or does it do some kind of workaround like the uinput trick?
I tested it on Plasma 6. If I interpret the extest Readme correctly it uses the uinput trick. So I guess that it works with older versions as well. Maybe without the plasma integration.
Sorry, didn't realize that the link is to extest's repo.
It seems that this actually undoes wayland's protection against any program inserting fake input events, and it does not only allow onboard to do so.
I thought that it was already possible with onboard, with selecting uinput instead of xtest in the settings. Never tried though, because I didn't want to undo that security measure.