Mouse Actions

Basic mouse actions in the interface use mouse button 1 or button 2. By default, button 1 is the leftmost mouse button and button 2 is the rightmost button. The system allows the user to swap the mapping of the buttons. Button 2 actions typically duplicate functions already accessible with button 1, but provide those functions more efficiently.

Note
For a mouse with three buttons, button 2 is the rightmost button, not the center button.

The following are the common behaviors performed with the mouse.

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.
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.
Pressing	Positioning the pointer over an object and then holding down the mouse button. Pressing is often the beginning of a click or drag operation.
Dragging	Positioning the pointer over an object, pressing down the mouse button while holding the mouse button down, and moving the mouse. Use dragging for actions such as selection and direct manipulation of 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, there is no basic action defined for a third (middle) mouse button. It is best to limit the assignment of operations to this button to those environments where the availability of a third mouse button can be assumed, and for providing redundant or shortcut access to operations supported elsewhere in the interface. When assigning actions to the button, you need to define the behaviors for the actions already described (pointing, clicking, dragging, and double-clicking) for this button.