I am thinking that this is one of the situations where the words “active” and “selected” may cause confusion.
In several of the collections, the “active” member can differ from the “selected” member.
But (after testing manually in SU2018) it appears that the two words have the same meaning for the styles collection. Whatever is selected is what the active style is that is used to render the viewport.
When I have a model with 3 scenes, each with it’s own style setting, the “selected” style (in the Styles inspector panel) changes to match which ever style is used for the scene page I choose.
If I were to delete the 3 scene pages and just have a single model view, whichever of the 3 styles I “select” becomes the “active” style for the model.
So it appears that the C API’s function to change the model’s global style would be:
@thomthom, can you confirm ?