It`s a very nice and helpfull demo set and used codes are published ad different places and well documentated. Great Thanks for all of this. Nevertheless in other scanarios there is a button "open in Greenfoot environment". Here it is especially needed to see the configuration of Word, Subwold, Actor, Subactor and/or Helpclass. Please can you give this posibilities also here. (a lot of browsers don`t support applets, as all ready known) Thanks Yogibaer

@Yogibaer, nothing is special about class configurations -- and the Scroller class is not directly linked to the World or Actor class, but is a "help class" in itself extending the Object class (the root of ALL classes). A subclass of world that is to scroll will create a Scroller object and tell it when and how much to scroll. That is basically it.