Currently you can only use the Tablet Layout when creating a blank app. Can you please include this layout when generating an app from a data source? I really think this should be a high priority. The option to switch between layouts would be nice too.
It takes a long time to build an app from scratch, particularly as the gallery control in a blank app does not seem to find fields/columns in the data source (I've updated the Items formula, but it cannot find the columns, despite having used them successfully in the same app generated using Phone Layout).
This feature idea is actively being discussed and we see the value it will bring. If as part of it we were to support incrementally adding entities to an existing app with the predefined templating of the current App from Data, would that be useful?