A unified visual design environment in a data processing system to enable automatic generation of a plurality of stylesheets for different output formats. The invention enables support for visual editing and generation of extensible Stylesheet Language (XSL) code, such as XSL code that enables XML content to be rendered into an HTML file, XSL:FO code that enables XML content to be rendered into a PDF file, and the like. With a single stylesheet design, developers can preview an output of a stylesheet transformation in one of several different formats, e.g., HTML, PDF, or others.