Diagram Designer's main window displays the application menu and toolbar, a list of the components in your diagram, a preview of the diagram and the forms you can insert. 

The Diagram menu gives you access to the Spell Checker, to the Page properties and also allows you to edit layers and to change their color. 

The Object menu allows you to customize various properties of your objects: group, rotate, align, etc. 

Diagram Designer's Options window enables you to configure the application's behavior according to your needs and preferences.