Summary: We present a strategy and algorithms for displaying a meaningful view of structured objects such as programs on a screen of limited size. The methods introduced here are language-independent; they were developed for the implementation of Cépage, a structural editor making full use of modern display technology. The algorithms are linear with respect to the number of nodes in the syntax tree. We use a formal model of the screen allocation, the "calculus of windows", which makes it possible to reason about the display process at a proper level of abstraction. A systematic approach was followed, in which a number of "invariants" and "attributes" were defined before the actual construction of the algorithms and data structures, and served as a basis for their development; the paper describes the methodology used and includes a semi-formal correctness proof of the main algorithm, which involves mutually recursive procedures.