Similar to creating a solution, the user can pick either "Start with a template" or "Create from Scratch", (which is a collection of predefined apps) let the user select a predefined "template app" from the app library. In many cases I needed an app in Solution A which is almost identical to an app in Solution B. for example "clients", "users", "invoices" ... + Let users add apps they have created to the library. (they'll see apps by SmartSuite and apps they have added)
