Question about multi-worlds

[DrMasik]

you could try with bungee buttons or write an own plugin

I'm wrote my own plugin.
Player connect to default world and have 3 buttons. The buttons controlled by plugin. When player press some of them (HOOK_PLAYER_RIGHT_CLICK), plugin use cPlayer:MoveToWorld (http://apidocs.cuberite.org/cPlayer.html) to move player.
Server crushed.