The Project Window can be toggled on and off by running the Project Window command. You can activate and set the focus to the Project Window by running the Activate Project Window command.
The Project Window is a floating/dock-able window. By default it contains all the Project-List sub-window panels:
Project Symbol List - quick access to all symbols in the project. See: Project Symbol List.
Project File List - quick access to all files in the project. See: Project File List.
Project Symbol Categories - See: Project Symbol Categories.
Project Folder Browser - See: Project Folder Browser.
Project File Types - See: Project File Types.
If the Context Window is open, then it will display the contents of any file or symbol selected in the Project Window.