Block editors such as the one used in Scratch are now found in many visual programming languages (VPLs). While considered user-friendly for nonprogrammers or program learners, they have at least three important display limitations: readability, program structure, and re-use. To address these issues we have developed block shelves, a formatting and organizing tool in support of user-defined VPL structures. Usability experiment results indicate that block shelves can significantly enhance block code navigation and searches, as well as project structure clarification. In the interest of improving project collaboration and code re-use, users can utilize the extensible markup language file format to export/import shelves, and thereby share block codes between projects. Features designed for shelves and the experiment findings are value for course design in project-based learning and future block editor interface improvements.

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