Online discussion forums are one of the most ubiquitous kinds of resources for people who are learning computer programming. However, their user interface - a hierarchy of textual threads - has not changed much in the past four decades. We argue that generic forum interfaces are cumbersome for learning programming and that there is a need for a domain-specific visual discussion forum for programming. We support this argument with an empirical study of all 5,377 forum threads in Introduction to Computer Science and Programming Using Python, a popular edX MOOC. Specifically, we investigated how forum participants were hampered by its text-based format. Most notably, people often wanted to discuss questions about dynamic execution state - what happens "under the hood" as the computer runs code. We propose that a better forum for learning programming should be visual and domain-specific, integrating automatically-generated visualizations of execution state and enabling inline annotations of source code and output.