Inside Macintosh: Macintosh Human Interface Guidelines / Part 2 - The Interface Elements: Chapter 4 - Menus

Hierarchical Menus

Hierarchical menus are menus that include a menu item from which a submenu descends. You can offer additional menu item choices without taking up more space in the menu bar by including a submenu in a main menu. When the user drags the pointer through a menu and rests it on a hierarchical menu item, a submenu appears after a brief delay. To indicate that a submenu exists, use a triangle facing right, as shown in Figure 4-36.

Figure 4-36 A hierarchical menu

Submenus add complexity to the interface. They hide choices from people by adding a layer to menus. They are physically more difficult to use than menus that pull down from the menu bar. You should use a submenu only when you have more menus than fit in the menu bar. Figure 4-37 shows an example of unnecessary submenus.

Figure 4-37 Don't use submenus unnecessarily

When you use submenus, include them in a menu with a logical relationship to the choices they contain. In the example shown in Figure 4-38, the submenus are in the logical menu. However, since there is still space available in the menu bar, it's questionable whether the submenus should exist. They would be more visible as main (pull-down) menus in the menu bar. Fonts should always be in their own separate menu because users often have very long lists of fonts.

If you find that there is still a lot of space between your last menu title
and the standard menus (Help menu, Keyboard menu, and Application menu), it's best to continue to use standard pull-down menus instead of hierarchical menus.

Figure 4-38 shows an example of a 9-inch screen that still allows room for more menus. The Size and Style submenus would fit in the menu bar.

Figure 4-38 A menu bar on a 9-inch screen with space for more menu titles

Hierarchical menus work best for providing a submenu of attributes. A
menu item that's the title of a submenu should clearly represent the choices it contains. It's much easier to identify a set of attributes than a set of verbs (actions). Figure 4-39 shows the difficulty of naming a menu item so that
it serves as a descriptive title for a submenu of commands. The figure also shows an appropriate title for a submenu of attributes.

Figure 4-39 Examples of submenu titles

A main menu can contain both standard menu items and submenu titles.
You may assign keyboard equivalents to menu items in either a main menu
or a submenu. Follow the guidelines presented in the section "Keyboard Equivalents," which begins on page 100.

Never use more than one level of submenus. A submenu at the second level would be buried too deep in the interface and would unnecessarily create another level of complexity. Also, it takes more time for the user to use
and peruse a hierarchical menu than a pull-down menu. It is physically difficult to use a second level of submenus without slipping off the first submenu. Figure 4-40 shows an example of a technique to avoid using
with submenus.

Figure 4-40 Avoid more than one level of submenus