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

Toggled Menu Items

A toggled menu item changes between two states each time a user chooses it. It's like a toggle light switch, when you flip it one way, the light turns on. When you flip the switch the other direction, the light turns off.

There are three types of toggled menu items. In one type, there is one menu item and its name changes to reflect the current state of the item. An example of this type is the command Show Ruler, which changes to Hide Ruler when the ruler is visible in the document. Another type of toggled menu item has one menu item that has a checkmark next to its name when it is in effect. An example of this type of item is a style attribute like Bold. The third type of toggled menu item has a group of two menu items that are opposite states. The state currently in effect has a checkmark next to its name.

If you have room in your menu, it's a good idea to use two menu items
that describe opposite states. The user can see both items at once, and
there's less chance of confusion about the effects of the menu items. Set
the items off using dividers to indicate that this is a related set of menu items. Use a checkmark to indicate the active item, as described in the section "Checkmarks and Dashes in Menus" on page 57. Figure 4-30 shows a
set of properly constructed toggled menu items.

Figure 4-30 A set of toggled menu items

If you don't have room in your menu for two items, you can use one item (which describes a specific action) and change its name to the opposite action when it's chosen. When you use a toggled menu item that is only one item, you must be sure that the name of the command is completely unambiguous. The command names should be verbs that express opposite actions. In the previous example, you could change the phrase Grid On to Turn Grid On. The command becomes Turn Grid Off in the opposite state. Figure 4-31 shows this solution.

Figure 4-31 A single toggled menu item whose name changes

In this menu, Turn Grid On clearly means that the grid appears when the user chooses the command. Then the command name changes to a clear statement of what happens as a result of choosing the Turn Grid Off command.

Try not to use phrases that could have ambiguous meanings. For example, does Use Grid mean that

the grid is on?
this command turns on the grid?

Figure 4-32 shows two different expectations of what the user might see when the Layout menu is opened after choosing the command Use Grid. In this example people have to choose the command, see what happens, and look at the menu to see what the meaning of Use Grid is.

Figure 4-32 An ambiguous toggled menu item

Don't use one menu item with a toggled checkmark to indicate the presence or absence of a feature like a grid or a ruler. It's unclear whether the checkmark means that the feature is in effect or whether choosing the command turns the feature on. In the example shown in Figure 4-33,
a checkmark next to Grid On could mean the grid is on, but the absence of a checkmark wouldn't be a clear indication that the grid is off. Because
any change to the user's content or working environment should be visible on the screen (in the application or in the Finder), not hidden, don't use the menu as an indicator of the current state by placing a checkmark next to a single, ambiguous menu item.

Figure 4-33 An incorrect use of a checkmark to indicate a state