The Project Manager is one of the oldest tools built into VFP, and it has showed its age for a long time. For example, it doesn't provide integration with modern distributed version control systems (DVCS) such as Mercurial and Git, it doesn't have a way to filter or organize the list of items, and it can only work with one project at a time.
Project Explorer is a VFPX project that replaces the Project Manager with a modern interface and modern capabilities. It has most of the features of the Project Manager but adds integration with DVCS (including built-in support for FoxBin2PRG and optional auto-commit after changes), support for multiple projects within a "solution," allows you to organize your items by keyword or other criteria, and has support for easy "auto-registering" addins that can customize the appearance and behavior of the tool.
See ProjectExplorer.pdf for documentation on Project Explorer.
A video is available showing Project Explorer and how it works.
See the change log for release information.
See How to contribute to Project Explorer for details on how to help with this project.