Change and improve PlaceholderMessage new API
This MR is essentially a proposed correction for !229 (merged).
The way that change was implemented involved an unnecessary compatibility item and unnecessarily changed the styling for the newly-added thing that made it visually incompatible with the existing style. We can implement the feature differently to save some memory in a way that avoids that problem and preserves the existing styling.
Also change one of the API documentation examples to use the new API.