You can normally access this dialog by pressing Alt0, or choosing the "Window | Other..." menu
The main menu or simply menu is a horizontal bar with clickable commands anchored to the top of the main window of Atlantis:
command (when you have 10 or more documents open).
This dialog displays the list of documents currently open in Atlantis.
To activate a document, click its filename, then press the OK button. Alternatively, just double-click the document filename.