There is a large number of interactive visualization tools, however no universal tool exists that covers all relevant aspects for all possible application domains. We have developed a tool, ComVIs, which was intended to be used as a research prototype for new visualization techniques. We have identified some interesting aspects from developers and users point of view during tool development. In this paper we describe lessons learned during the process, and share our findings with visualization research community. Examples at the end prove the usefulness of the developed tool. One particular example, the concept of families of function graphs and application to analysis of fuel injection concludes the paper. Keywords— Information visualization, visual analysis, visualization tool, system design.