Visual programming is a powerful and appealing technique for building complex applications using domain-specific programming environments. In this article we argue that a visual methodology and interface seems to be important for the end-users of such environments, who are experts in their domain, are not software engineers, but wish to create complex applications. Many domains, including plant control and systems engineering are well-suited for visual specification. Recognizing this, a configurable visual programming environment (VPE) has been developed, customized and subsequently used by engineers in the field. The VPE is the programming interface in model-based systems which achieve automatic software synthesis through the use of domain-specific models. This article discusses the requirements and the design of the generic VPE, and describes its use in the process control domain. Variants of the VPE have been used at Boeing, DuPont, NASA, and Osaka Gas, Japan.