One of the most frequently asked questions about VISTA is
``why didn't you use the existing software X to build on and solve the problem, instead of re-inventing the wheel?''
The answer to this simple and fair question is rather complex. Most importantly, a framework implementation for such an aggressively evolving discipline as technology CAD must be something one can rely on. Considering the large number of applications from which we expect that they rely on the framework as enabling and supporting environment, it is obvious that the framework, as vital component and backbone of the entire system, must exhibit the utmost stability. Uncontrollable, unsynchronized, and incompatible versions of framework components are simply not tolerable. Overly outdated versions of these components are not acceptable either. The overall system, if glued together from ready-to-use components will very likely exhibit no conceptual integrity and will be entirely incomprehensible. Moreover the system will only run on the intersection of the sets of supported platforms of all constituent components.