Solution:
1. Get file from sddm-greeter and startplasma-x11 (aka KDE) processes as well
2. Get users home dir from system instead of hard coded pattern /home/<user>
3. Prefer XAUTHORITY environment variable over Xorg -auth if available
Windows renames files adding (1), (2) etc. before the .exe in case
of duplicates, which causes the host or key values to be garbled.
This allows to protect from this adding a final "#" symbol to the
filename.