In a somewhat tongue in cheek answer to https://blender.stackexchange.com/a/197340/15543 have come across the possibility of having one instance of a 3d view showing a different theme than another.
Updating a space theme color within a draw callback, and again, is setting the colour for an instance. Any bgl required is being done for us. (Not the right one, shows the concept. Code was cobbled together for a question revolving around a scene property (same scene per screen))
Feel this could be useful https://blender.stackexchange.com/a/161773/15543 in finding a combination of region and event type.
The question.
How can I harness this to show another theme (or one colour of as above will suffice) based on a space property correctly. per instance.
My particular use case is being able to "theme" a particular script in the text editor
