The Multi-Class Hierarchy window displays a complete graphical map of the classes in the browser database. Each class name is displayed in a box, and related classes are connected to each other by lines. Choose Class Hierarchy from the Window Menu to display the Multi-Class Hierarchy window. Figure 7.7 shows the Multi-Class Hierarchy window.

Use the arrow keys to change the selected class "geographically." The up and down keys work on siblings. The left and right keys work on ancestors and descendants.

You can use the keyboard to change the selection. The current selection most closely matches the characters you type. Use the Tab key to change the selected class alphabetically.

If you double-click a class entry, or select the entry and press the Enter/Return key, you open a Browser Window for that class.

In addition to the entry for each class, the Multi-Class Hierarchy window has three items:

• Line button
• Hierarchy expansion triangle
• Ancestor Class pop-up menu

The Line button controls the display of the lines that connect related classes. You can toggle between diagonal lines and straight lines. The choice is entirely aesthetic.

The hierarchy expansion triangle controls the display of subclasses.

If you click this triangle, the next level of subclasses is displayed or hidden from view. To be more precise, the expanded state restores to what it was the last time this class was open.

Click on the Ancestor Class triangle, shown in Figure 7.7, to display a pop-up menu. This menu lists immediate ancestors. When you choose an item from the pop-up menu, you jump to that class in the map. If the item is not currently visible, the computer beeps.

This control is displayed only for classes that have multiple base classes.