I am using a Thinkpad T520i (Intel(R) Core(TM) i3-2310M CPU @ 2.10 GHz; 16 GiB
RAM, 500 GB SSD Disk) with openSuSE Leap 42.3 (Currently Kernel
4.4.114-42-default, X.org X Server 1.118.3, KDE Framework 5.32.0, QT 5.6.2,
xf86-input-libinput-0.25.1-1.1.x86_64, libinput-udev-1.5.0-3.5.x86_64,
libinput10-1.5.0-3.5.x86_64) and a while ago I first encountered the problem,
that native KDE-Applications don't get any keyboard input after unpluggin and
replugging the keyboard (e.g. when undocking and redocking the thinkpad to a
dock with an usb keyboard)
Using the Thinkpad with a dock and a USB-Keyboard connected to it makes this
usage quite uncomfortable.
The only workaround I could find is logging out and logging in again. Then
everything is working again, but as it requires me to stop my work and restart
all applications this is not a feasible workaround.
This only happens with KDE Applications (plasmarunner, plasmamenu, kate,
konsole, etc) not with X, GTK or even simple QT Applications), all other
applications just work fine with any keyboard (internal Thinkpad, external USB,
virtual Keyboard application) wheres KDE applications with none of those
keyboards, not even the virtual keyboard.
The keyboard is also listed in the xinput output after replugging it (run from
an xterm as konsole isn't taking any keyboard input anymore). The USB mouse is
just working fine. So it definitely doesn't look like a hardware, driver or X
problem, but like something caused by the common code used by kde applications
for doing input. The Bug is probably also already present in older code as I
never used an USB keyboard or the dock before I didn't encounter those
problems.
I even tried the workaround from the almost similar sounding bug description of
BUG 988792 by running 'killall plasmashell ; kstart plasmashell' but this
doesn't work for me.
Neither does deactivating /etc/X11/xorg.conf.d/40-libinput.conf and using evdev
driver instead of libinput as BUG 1044820 suggests as a solution/better
workaround.
Frankly I'm not sure which log files, config files, config settings, command
output paste or other information I could provide to make tracing this bug
behaviour to specific code lines easier, but If you point me in a direction,
I'll provide that information gladly.