Volume 6A: Motif Programming Manual

16 Menus

This chapter describes the different types of menus provided by the Motif toolkit. It also presents a number of ways to

create menus in an application and talks about the issues involved in designing menu systems.

Menus provide the user with a set of choices in an application without complicating its normal visual appearance.

These convenient mini−toolboxes are essential for the user who, like an auto mechanic that is busy working under the

car, needs quick and convenient access to her tools without having to look or move away from her work. The Motif

Style Guide provides for three different types of menus: PulldownMenus, PopupMenus, and OptionMenus. Despite

the differences between the three types of menus, they all provide simple and convenient access to application

functionality.

16.1 Menu Types

PulldownMenus that are posted from the MenuBar are the most common menus in an application. the figure shows an

example of a PulldownMenu. The menu pops up when the user presses the first mouse button on a CascadeButton.

The button that posts the menu is typically user−settable, since left−handed users may want to reverse the default

button bindings. As described in Chapter 4, The Main Window, CascadeButtons may be displayed as titles in a

MenuBar or as menu items in a PulldownMenu. When the CascadeButton is a child of a MenuBar, the menu drops

down below the button when the user clicks on it. When the CascadeButton is an item in an existing menu, the new

menu pops up to the right of the item; it is sometimes referred to as a cascading menu or a pullright menu.

A PulldownMenu

Under certain conditions, it may be inconvenient for the user to stop what she is doing, move the mouse to the

MenuBar to pull down a menu, and then move the mouse back to where she was working. Having to move the mouse

away, even to another part of the same window, can reduce productivity. A PopupMenu is one solution to this

problem as it can provide immediate access to application functionality. PopupMenus are posted using the third mouse

button and can be displayed anywhere in an application. Rather than having to move the mouse, the user can simply

431

press the third mouse button to cause a PopupMenu to appear on the spot. This type of menu does not need to be

associated with a visible user−interface element. In fact, PopupMenus are usually popped up from a work area or

another region that is not affiliated with a user−interface component like a PushButton or CascadeButton. The only

drawback to this design is that there is no indication to the novice user that the menu exists. the figure shows a

PopupMenu.

A PopupMenu

The OptionMenu combines the strengths of a PulldownMenu and a PopupMenu. Like a PulldownMenu, it is posted

from a CascadeButton, but like a PopupMenu, it can be placed where it is needed. The CascadeButton is used to

display the default choice for the menu. When the user presses the button, the alternate choices are displayed in a

menu, as shown in the figure. Like a PulldownMenu, an OptionMenu is invoked using the first mouse button, but it is

displayed on top of its associated CascadeButton rather than below it.

16 Menus 16 Menus

432

An OptionMenu

The use of the third mouse button to activate PopupMenus is in sharp contrast to PulldownMenus and OptionMenus,

which are always invoked by the first mouse button. It may seem confusing to the user that some menus are invoked

by the first button while others are invoked by the third. However, there is some consistency in the fact that

PulldownMenus and OptionMenus are always attached to CascadeButtons, and buttons are always activated by the

first mouse button. By specifying that PopupMenus use the third mouse button, the first mouse button is free to be

used for other activities in an application work area, which is important since PopupMenus can be popped up

anywhere in an application.

When the user posts a menu, it is only displayed until the user makes a selection, and then it is removed. In Motif 1.2,

a menu can have an additional feature that allows it to be torn off, so that it remains posted in its own window. The

tear−off functionality is activated by a special tear−off button in the menu. The button displays a dashed line to

indicate that you can tear off the menu, like you would tear a coupon out of a newspaper. When the user presses the

tear−off button, the menu is placed in a separate window, and the user can make as many selections as she would like.

the figure shows a PulldownMenu that provides the tear−off capability.

A Pulldown Menu with tear−off functionality

To make menus even more convenient to use, menu items can have mnemonics and accelerators associated with

them. These devices are keyboard equivalents that allow the user to activate menu items using the keyboard rather

than the mouse. For example, in the figure, the underlined letter in each menu item is its mnemonic. While the menu is

posted, the user can type the specified character to activate that menu item. Accelerators are keystroke combinations

16 Menus 16 Menus

433