For example, if you close window B in the example above, FractaSketch warns you that A and B are not saved. This is backward transitive closure. E. This is backward transitive closure again. Infinite drawing levels. FractaSketch doesn't actually ever go into an infinite loop with the infinite drawing levels, because it has a maximum number of levels.
Mutual recursion is the most general form of recursion.
FractaSketch can handle mutually recursive templates easily.