The editor
The editor is an entered place: open a project and it fills the screen; Back returns you to the dashboard.
The center is the editing surface. Around it sit three equal tab slots (left, right, and bottom), each resizable, each taking whatever tabs you open in it. A fresh project opens with the Layout tree on the left, the Map on the right, and the bottom hidden until summoned.
The Layout tab lists the project's screens, each owning its own subtree. Click anything that lives on another screen and that screen opens in the center. The Map tab is the everything-canvas; see The Map.
Publish/Export sits top left. It opens the one project screen (publishing and settings on a single full-screen surface), and Go back returns you exactly where you were.
The editor renders, it never runs
Opening a project fires nothing. Operations run where the project is deployed, or when you explicitly run one from the editor.