I installed minicd of ubuntu 18.04 and then installed fvwm with Russian language.
Switch shift+alt works well and xxkb and gxkb works well. I need for portuguese and I
installed it by sudo apt-get -y install ‘check-language-support -l pt’. But shift+alt
switches Russian and English, only. How add pt for shift+alt switch? setxkbmap pt
changes language total to portuguese and then xxkb and gxkb and shift+alt do not work.
I found that it was conflict between xxkb and gxkb. I started gxkb only and added in
its config third language pt and now everything is ok. Question is closed 