1. A graphical application development environment, adapted for the development of user-defined test, measurement or process control applications, said environment comprising: (a) a graphical desktop providing user access to a plurality of selectable panels; (b) at least one data source type panel for providing access to a source of streaming data; (c) at least one data sink type panel for receiving streaming data from a data source type panel and for displaying a representation of such streaming data on said desktop; and (d) at least one controlling type panel for controlling a property of another of said panels, (e) wherein there is associated with each of said panels an aspect-type software object that comprises attributes and properties embodied in executable code segments.