Modify command on powersave-idle-shutdown

Hi,

Since my update to Ubuntu 16.04.01 LTS I need to use “shutdown -P” or “poweroff” command to Poweroff my machine.
I dont know why since /etc/defualt/halt sets HALT=poweroff … but therea are some compareable bugreports in Ubuntu …
anyway my question:

When I manually shutdown my machine I could define a shutdown command in DialogButtonMenu.xml.That works well.
But .. I normally use the powersaving feature of kodi which shuts the machine down on x-min idle.
How to define the command, which Kodi uses for that?
I believe it’s the Callback “XBMC.poweroff()”, but I dont know how to configure the behaviour of that Sad

Any help appreachiated!

BR – Disky