What you are referring to is called 'scrolling'. Try a search on 'scroll' or 'scrolling' or 'scrolling world' or 'scrolling actor' or something similar and review some of the discussions; maybe download some scenarios with scrolling support classes and see how they are done. There are several types, and one may be more like what you are looking for than another (there are several factors that make one more suitable than another; such as (1) will it scroll infinitely or be limited to a certain size; (2) if limited, is it limited by the size of an image or to a specific width; (3) will your main actor be able to roam some within the window before scrolling or not; (4) will it scroll just horizontally, just vertically, or both; etc.)