The menu and desktop short cuts are unresponsive until I kill the X server and restart (other stuff works)
I’ve tried to cure it by deleting .kde4 but this does not solve the problem
I’ve always steered away from fiddling with the X server, so have little experience of playing with it, but I assume there must be a corrupt config file?
and I cannot preserve my system keyboard settings - they revert to English (US) after every reboot after editing
YaST->System->Language and YaST->Hardware->System Keyboard Layout (it was set to UK already, so I set it to something else first).
/etc/sysconfig/language reports
# Local users will get RC_LANG as their default language, i.e. the
# environment variable $LANG . $LANG is the default of all $LC_*-variables,
# as long as $LC_ALL is not set, which overrides all $LC_-variables.
# Root uses this variable only if ROOT_USES_LANG is set to "yes".
#
RC_LANG="en_GB.UTF-8"
/etc/sysconfig/keyboard
# Keyboard mapping
# (/usr/share/kbd/keymaps/)
# e.g. KEYTABLE="de-latin1-nodeadkeys", "us" or empty for US settings
#
KEYTABLE=""
.kde4 is not where current or recent versions of Plasma store much of anything. Plasma5 settings are mostly in ~/.config/, mixed up with many other personal settings. Your problem suggests to me a permissions problem in your homedir. If you login as a new user, is the trouble the same?