The numerical/theoretical parts of the POINCARE demo use "boxed" statements or formulas to highlight important ideas. This is a familiar device used in many math texts; here it is also used as a metaphor to indicate the presence of something "behind" whatever is in the box - a statement, an example, a formula . . .. The boxes appear raised to indicate the presence of something behind them (i.e. a link to related material), and appear depressed after the link is followed (for contrast). [The art-work for these boxes needs re-doing to show this distinction more clearly.]