The Main Screen normally contains Project Window, Design Window and Output Window. When a WML file is opened, the Design Window is split into Card Pane and Control Pane. The cards relating to the file are shown in the Card Pane and the WML controls relating to the card are displayed in the Control Pane.
The Main Screen also contains the Menu Bar, the Tool Bar and the Design Bar. Normally, they appear at the top of the screen and are dockable.