A small addon that adds support for drawing colourful overlays over user-defined face groups and works in Edit Mode. A nice-to-have when doing retopology and marking key loops or just studying topology.
The workflow is very similar to marking faces with different materials and behaves similarly when editing the mesh. However, the overlay is drawn based on a custom data layer instead, therefore the addon does not interfere with any other data that could be used for other purposes and can be viewed in different viewport shading modes. A pie menu and additional options are also provided.
Note that the first version may still contain bugs. Issues can be raised on GitHub. Back up your project before testing!