A previous report identified several usability and learnab ility problems with integrated development environments (IDE) for Java. That report also cast these problems as examples of a conceptual gap between developer mental models and how programs are represented in IDEs. This present study extends the previous work through heuristic and psychometric assessment of problems reported by both experienced and inexperienced developers in their use of an IDE for C++. The results indica te that both groups identified similar kinds of ease-of-use problems, especially concerning program learnability and visibility (e.g., the usefulness of error and help messages). These find ings are d iscussed in relation to other research results about developers? experiences with CASE tools and conceptual gaps between the too ls and their users.