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Motif and CDE 2.1 Style Guide

Pointing Devices

A pointing device enables the user to move a pointer on the screen and to manipulate interface elements directly. Most keyboard actions can also be accomplished using a pointing device.

The most common pointing device is the mouse; however, a graphics tablet and stylus, pen, track ball, joystick, and other tools are also pointing devices. The model in this book uses the mouse as the pointing device.


The mouse is the most common pointing device and contains one or more buttons with which a user can interact with an application or the operating environment. The actions users perform with the buttons vary depending on the functions assigned to each mouse button. You can map functions to buttons in different ways; therefore, the descriptions in this book actually describe virtual mouse buttons. Button names given when describing a user's action represent either a particular mouse button or a combination of buttons and actions that the user performs to complete a task.

This book uses the following virtual mouse button names:

Selects elements, directly manipulates elements to change values, activates elements, and moves the cursor. This is always the leftmost button for right-handed users.

Adjusts selections. This is always Shift SELECT. It may also correspond to the middle button on a 3-button mouse.

Transfers and manipulates elements. This is usually the second mouse button; or it can be the same button as the SELECT button, in which case a single button is used for selection and transfer.

Displays a pop-up, cascaded, or pull-down menu. The MENU button can also be used to activate elements within a menu system. This is always the rightmost button on a 3-button mouse for right-handed users. On a 2-button mouse Alt SELECT can be used instead.

Left-handed users can switch the mouse buttons to be the reverse of the previous descriptions.

The user can combine the use of the mouse buttons to perform different tasks; this is called a chord. A chord is performed by clicking or pressing two or more mouse buttons (not necessarily simultaneously) so that the buttons have the effect of being pressed at the same time. That is, the user presses one button, holds it down, and then presses another button.

For information about binding application functions to pointing device buttons and about the virtual mouse buttons, see the Mouse (Device) reference page and Appendix C. "Mouse Techniques".

Mouse Techniques

The following list describes mouse techniques:

Moving the mouse, which moves the pointer in the interface.

Pressing and holding down a mouse button. A press can initiate an action, such as dragging an object to a printer icon.

Press and move
Pressing a mouse button without releasing it and then moving the position of the pointer, such as moving an element (like an icon) across the screen.

Releasing a mouse button after pressing it. Releasing the mouse button performs an action initiated by pressing it, such as activating a push button.

Pressing and releasing a mouse button without moving the pointer. Clicking a mouse button can perform an action such as activating a menu item.

Performing two clicks in quick succession. A double-click performs the default action of a control. The time interval between clicks can be user defined.

Performing a number of clicks in quick succession.

Performing one click followed by a press in quick succession without moving the pointer.

Performing a number of clicks followed by a press in quick succession without moving the pointer.

Mouse Motion

Two concepts define how the pointer tracks the motion of the mouse: gain and acceleration.

Gain refers to the ratio of distance the pointer moves to the distance the mouse moves. If the gain is increased, the pointer moves farther for a given mouse movement. The gain remains constant across the environment.

Acceleration refers to a change of gain based on the speed of mouse movements. The user can set the acceleration so that the gain is increased if the mouse is moved quickly, allowing faster pointer movement. If the mouse is moved slowly, the gain is reduced to allow finer pointer position adjustments.

Gain and acceleration are handled on a global scale by the operating system. Unless your application involves user configuration of mouse motion, your application should not change the gain and acceleration characteristics of mouse movement.

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