Two major problems encountered in software systems development using components built by other people are: component interfaces can be informal and often incomplete that they don't fit together; and software complexity and inability to foresee or determine the consequences of changes. These problems result from three essential and intertwined properties of software systems development: composition, evolution and complexity. While the first can be addressed by using formal interface specifications, the other two needs careful analysis. The concept of light semantics is discussed with regards to addressing the problems of software evolution and complexity, with Inscape as an example.