The challenge to developing applications for computer-based windowing systems is generating code for the graphical interface elements. Each windowing system offers its own set of protocols for building the graphical units, but these protocols are rarely portable across different hardware platforms. The X Window System transcends many of these incompatibilities and offers a standard for creating graphics. It is operating system and network independent. However, the basic programming library for X Window offers little sophistication for an application's graphical interface development. Higher level tools make up for the shortcomings of the generic X Window System. This thesis converts an Expert System Knowledge Acquisition and Policy Evaluation program using Cognitive Feedback (ESKAPE/CF) from the SunView windowing system to X Window. The new application, called XESKAPE/CF, contains the same functionality as the original program even though the migration from SunView to X Window required an extensive reworking of the program's interface code. The thesis also extends the basic X Window library of functions with more advanced objects. These objects offer additional functionality to the XESKAPE/CF application's interface.