There are multiple sides to this issue.
- we don't draw an overlay for it.
- the calculation of the colors was in blender 2.79 a per mesh attribute, now it is a 3d view attribute.
The activation of the drawing should trigger the calculation of the colors (draw_cache_mesh).
What colors will be shown is currently a tool setting. also the data is stored in the BMesh (derivedVertColor, derivedFaceColor)
So question is how far will we implement this. eg. should the tool setting become a per view setting (and therefore the data will also be placed there).
Note to self:
- change derivedVertColor and derivedFaceColor to weight. Assign color in shader.