Select View - Project Editor View to open an Edit tab in the session window with a 2D view of the project in the presently selected 3D tab. If a 2D Edit tab is already open for the project, then the existing tab is selected and displayed. If a 2D Edit tab is not open for the project, a new 2D tab is opened and displayed.
NOTE: This command is only available when looking at a 3D view.