System Settings > Keyboard > Virtual Keyboard: IBus Wayland selected
There are three input methods (European languages), but the Next input method shortcuts work with stops and hitches; I’ve no idea how to describe it better. So far I tried Super+Space and Shift+Space, no difference.
I have experience with IBus and KDE on X11; one has to know how to start IBus there, but the shortcuts give no problem.
I also know that on Wayland only Gnome is trouble free concerning IBus. But this can’t be forever, I hope. Please, share your experience. I searched everywhere, found next to nothing.
Super+space by default is in conflict with Shortcuts/Keyboard Layout /Switch to next…
Delete there if you want to use in ibus.
In /etc/environment added only
XMODIFIERS=ibus
IBus Panel mouse middle button fails to work and mouse right is ‘commited’ only if an input window is active.
The shortcut works strangely for me: space, up/down arrow makes the selection.