Many programming problems call for turning geometrical
thoughts into code: tables, hierarchical structures, nests of objects, trees,
forests, graphs, and so on. Linear text does not do justice to such
thoughts. But, it has been the dominant programming medium for the
past and will remain so for the foreseeable future.

This paper proposes a novel mechanism for conveniently extending
textual programming languages with problem-specific visual
syntax. It argues the necessity of this language feature,
demonstrates the feasibility with a robust prototype, and
sketches a design plan for adapting the idea to other
languages.