The Full Screen mode of Atlantis is fully customizable. On the View tab of the "Tools | Options..." dialog, you can specify which components of the Atlantis window will be displayed under the Full Screen mode:
By default, the main menu
The main menu or simply menu is a horizontal bar with clickable commands anchored to the top of the main window of Atlantis:
is not available under the Full Screen mode. But this main menu will appear if you ride your mouse against the top edge of the screen, and click:
When one menu item is visible, dragging the mouse cursor right or left along the top edge of the screen will display the other menu items.