Software development life cycle involves the activities of project management, requirement analysis and specification, architectural and system design, algorithm design, coding, testing, quality assurance, maintenance, and if necessary performance tuning. Throughout the development cycle, visual means have been playing an important rule in almost all the development activities, such as visual modeling using UML, design using flowcharts, and performance analysis using space-time diagrams, to name only a few. Interactivity among the visual components representing software artifacts and between software systems and the human (developers and users) is the key to the success of the visual assistance to the software development lifecycle.