Issuing that command:
setxkbmap -layout "us,ua,ru" -variant ",winkeys" -option "grp:shift_caps_toggle,grp_led:scroll" -model pc105 -rules xorg
When hitting Caps Lock+Shift I'm switching between English (us) and Ukrainian (ua) layouts, but not Russian (ru).
I've tried to reset it with the following command:
setxkbmap -layout "us,ua,ru" -option ""
and played with many different options - nothing helps.
My system is Gentoo Linux and window manager wmii.