Fundamentals of Designing User Interaction - Input Basics

Mouse Input

The mouse is the primary input device that users employ to interact with objects in the Microsoft Windows interface. The term "mouse" also applies to other types of pointing devices that emulate a mouse, such as trackballs.

More Information

For more information about interaction techniques such as navigating, selecting, viewing, editing, transferring, and creating new objects, see Chapter 6, "General Interaction Techniques."

Mouse Pointers

The mouse is operationally linked with a graphic on the screen called the pointer (also referred to as the cursor). By positioning the pointer and clicking the primary and secondary buttons on the mouse, a user can select objects and their operations.

As a user moves the pointer across the screen, its appearance can change to indicate a particular location, operation, or state. The following table lists some common pointer shapes and their uses.

Common Pointer Shapes
Shape	Screen location	Available or current action
	Over most objects	Pointing, selecting, or moving
	Over text	Selecting text
	Over any object or location	Processing an operation
	Over any screen location	Processing in the background (application loading), but the pointer is still interactive
	Over most objects	Context-sensitive Help mode
	Inside a window	Zoom-in view
	Over a sizable edge	Resizing an edge vertically
	Over a sizable edge	Resizing an edge horizontally
	Over a sizable edge	Resizing an edge diagonally
	Over a sizable edge	Resizing an edge diagonally
	Along column gridlines	Resizing a column
	Along row gridlines	Resizing a row
	Over split box in vertical scroll bar	Splitting a window (or adjusting a split) horizontally
	Over split box in horizontal scroll bar	Splitting a window (or adjusting a split) vertically
	Over any object	Not available as a drop target
	Over any object	Navigate to linked reference

Each pointer has a particular hot spot that defines the exact screen location of the mouse. The hot spot determines which object is affected by mouse actions. Screen objects can additionally define a hot zone, the area where the hot spot is considered to be over the object. Typically, the hot zone coincides with the borders of an object, but it may be larger or smaller to make user interaction easier.

Mouse Actions

Basic mouse actions in the interface use the primary or secondary mouse buttons. By default, the primary button is the left button and the secondary button is the right button. The operating system allows the user to swap the mapping of the buttons. Secondary button actions typically duplicate functions already accessible by using the primary button, but typically they provide a shortcut that's easier for the user.

Note

For a mouse with three buttons, the secondary button is the right button, not the center button.

The following table describes the common actions performed with the mouse.

Common Mouse Actions
Action	Description
Pointing	Positioning the pointer so it "points to" a particular object on the screen without using the mouse button. Pointing is usually part of preparing for some other interaction. Pointing is often an opportunity to provide visual cues or other feedback to a user.
Clicking	Positioning the pointer over an object and then pressing and releasing the mouse button. Generally, the mouse is not moved during the click, and the mouse button is quickly released after it is pressed. Clicking identifies (selects) or activates objects or hyperlinks.
Double-clicking	Positioning the pointer over an object and pressing and releasing the mouse button twice in rapid succession. Double-clicking an object typically invokes its default operation, such as selecting text or opening an icon.
Pressing	Positioning the pointer over an object, then holding down the mouse button. Pressing is often the beginning of a drag-and-drop operation.
Dragging	Positioning the pointer over an object, then pressing down and holding the mouse button while moving the mouse. Use dragging for actions such as selecting and directly manipulating an object.

For most mouse interactions, pressing the mouse button only identifies an operation. User feedback is usually provided at this point. Releasing the mouse button activates (carries out) the operation. An auto-repeat function — for example, pressing a scroll arrow to continuously scroll — is an exception.

This guide does not cover other mouse behaviors such as chording (pressing multiple mouse buttons simultaneously) and multiple-clicking (triple- or quadruple-clicking). Because these behaviors require more user skill, they are not generally recommended for basic operations. However, you can consider them for special shortcut operations.

Because not every mouse has a third button, no basic action is defined for a third (middle) mouse button. It is best to assign operations to this button only in environments where the availability of a third mouse button can be assumed or to provide shortcut access to operations supported elsewhere in the interface. When you assign actions to the third mouse button, you need to define the behaviors for the actions already described (pointing, clicking, dragging, and double-clicking).

Some types of mouse also include a wheel button that supports click-and-drag actions as well as a rolling action. Assign viewing operations — such as scrolling, panning, and zooming — to the wheel button.

More Information

For more information about using the wheel button, see Chapter 6, "General Interaction Techniques."

Fundamentals of Designing User Interaction

Windows Interface Components

Design Specifications and Guidelines

Appendixes and References