Human Interface Guidelines/Activities/Introduction
A New Model
We make a distinction between the typical single-application, multi-document model of computing and the Sugar full-screen activity interface, where each object (document) runs within its own instance—multiple instances of a given activity may run in parallel. Activity instances within Sugar provide a way to handle files as objects; each instance may represent a different group of collaborating individuals, and creating a new instance of the Draw activity implicitly creates a new drawing. "Open" and "Save" actions are relegated to a Journal interaction; In fact, we strengthen this by replacing the notion of "Saving" with the more general notion of "Keeping" things. To "open" a drawing you've kept, you simply resume it.