User Interface
- Model results are shown in the Display Area.

- Model Viewer provides five menus (File, Show, Action, Toolbox, Help).
- Each menu provides a drop-down list of commands.
- Grayed out commands are inactive.
- Certain commands can be alternatively invoked from the keyboard by holding
down the Ctrl key and then pressing a letter. This keyboard equivalent, when available, is indicated to the right of the command.
- The type of model and type of scalar data are indicated at the lower right
corner of the program window.
