Since styles_for_scope effectively ignore the font parameters (and instead return styles based on the font parameters used when the cache entry was created) it is a better design to have theme_t own the font. This way, changing it can do the proper cache invalidation.
A minor downside is that we can now change the font of the theme without also changing the layout’s font, which wouldn’t cause proper layout invalidation — since layout_t owns theme_t though, users of a layout should always change font via layout_t (which will then change it in the theme).
Also, themes cannot be shared between views that wish to use different font settings.
Given constraint-based layouts, we’re more likely to create views in code, and as helper functions are often involved, it makes sense to name them so that we can quickly get a list of all helpers (via search), either for copy/paste or for evaluating wether or not it makes sense to move all helpers to a single library.
Since helpers are declared with static storage, they do not pollute the global namespace.
