Hello. Currently using Kubuntu Bionic with KDE Frameworks 5.44, Plasma 5.12 LTS and KDE Applications 17.12.3. Even since Kubuntu Trusty using KDE 4.13.x, the number of maximum keyboard layouts in the KDE keyboard layout settings has been 8 and trying to add a new layout after that produces the error: "Only up to 8 keyboard layouts are supported". Frankly I don't see the reason for this artificial limitation. I myself know seven Indian scripts: Tamil, Devanagari, Kannada, Telugu, Malayalam, Grantha and Brahmi and do need to input all of them at one time or another. I also have a separate layout for the emoji I use. Which leaves me no space for even QWERTY, let alone my preferred alternate Latin layout Workman. I do not see the need for an upper limit on the number of layouts. Is there any technical reason why there needs to be such a limit?
Makes sense to me. Eike, is this something that will be resolved with your GSoC student's work?
The reason for this "artificial limitation" is that X11 only supports four keyboard layouts. Plasma already does some magic to support 8 with trickery. In the rewritten KCM, we will likely drop this and go back to only 4 for now. It might be possible to expand this trickery to support more than 8, but it's not a priority for now compared to addressing other limitations such as the lack of IM support. However, on Wayland there's no such limitation and you can have as many layouts as you want.
X-Only
So basically CANTFIX on X11 and ALREADYFIXED on Wayland.