How to get LibO writing Japanese in LM 18.3 KDE?

LibO 6.0 as it comes wiht LM 18.3 no changes made
Installed IBUS-Anthy from LM repository.
As Japanese writing did not work at all I added.

export GTK_IM_MODULE=ibus
export XMODIFIERS=@im=ibus
export QT_IM_MODULE=ibus

into ~/.bashrc
Result: Japanese writing works in Kate but not yet in LibO.

What needs to set to get LibO writing Japanese?

Thanks in advance for your help!