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The three-button scrollmouse has become the most commonly available design. As of 2007 (and roughly since the late 1990s), users most commonly employ the second button to invoke a contextual menu in the computer's software user interface, which contains options specifically tailored to the interface element over which the pointer currently sits. By default, the primary mouse button sits located on the left-hand side of the mouse, for the benefit of right-handed users; left-handed users can usually reverse this configuration via software.
In contrast to the motion-sensing mechanism, the mouse's buttons have changed little over the years, varying mostly in shape, number, and placement. Engelbart's first mouse had a single button; Xerox PARC soon designed a three-button model, but reduced the count to two for Xerox products. After experimenting with 4-button prototypes Apple reduced it back to one button with the Macintosh in 1984, while Unix workstations from Sun and others used three buttons. OEM bundled mice usually have between one and three buttons, although in the aftermarket many mice have always had five or more.
A mouse click is the action of pressing (i.e. 'clicking', an onomatopoeia) a button to trigger an action, usually in the context of a graphical user interface (GUI). "Clicking" an onscreen button is accomplished by pressing on the real mouse button while the pointer is placed over the onscreen button's icon.
The reason for the clicking noise made is due to the specific switch technology used nearly universally in computer mice. The switch is a subminiature precision snap-action type; the first of such types were the Honeywell MICRO SWITCH products. (See micro switch.)
Double clicking refers to clicking (and, naturally, releasing) a button (often the primary one) twice. Software recognizes both clicks, and if the second occurs within a short time, the action is recognized as a double click.
If the second click is made after the time expires it is considered to be a new, single click. Most modern operating systems and mice drivers allow a user to change the speed of a double click, along with an easy way to test the setting. Some software recognize three or more clicks, such as progressively selecting a word, sentence, or paragraph in a word processor text page as more clicks are given in a sequence.
From the first Macintosh until late 2006, Apple shipped every computer with a single-button mouse, whereas most other platforms used multi-button mice. Apple and its advocates promoted single-button mice as more user-friendly, and portrayed multi-button mice as confusing for novice users and that multiple button mice interfaces introduce computer accessibility restrictive elements[dead link] including right click, double click, and middle click.
On August 2, 2005, Apple introduced their Mighty Mouse multi-button mouse, which has four independently-programmable buttons and a trackball-like "scroll ball" which allows the user to scroll in any direction. Since the mouse uses touch-sensitive technology, users can treat it as a one-, two-, three-, or four-button mouse, as desired.
More recently, Apple has released a mouse with no buttons, but instead the touch sensitivity of the new Multi-Touch trackpads. This is called the Magic Mouse. Left and right click are available in their respective areas, but that space is also used when scrolling, since the mouse is simply one surface on the top. The standard optics of the Mighty Mouse appear on the underside of the new Magic Mouse.
Aftermarket manufacturers have long built mice with five or more buttons. Depending on the user's preferences and software environment, the extra buttons may allow forward and backward web-navigation, scrolling through a browser's history, or other functions, including mouse related functions like quick-changing the mouse's resolution/sensitivity. As with similar features in keyboards, however, not all software supports these functions. The additional buttons become especially useful in computer gaming, where quick and easy access to a wide variety of functions (such as macros and dpi changes) can give a player an advantage. Because software can map mouse-buttons to virtually any function, keystroke, application or switch, extra buttons can make working with such a mouse more efficient and easier.
In the matter of the number of buttons, Douglas Engelbart favored the view "as many as possible". The prototype that popularized the idea of three buttons as standard had that number only because "we could not find anywhere to fit any more switches".
On systems with three-button mice, pressing the center button (a middle click) typically opens a system-wide noncontextual menu. In the X Window System, middle-clicking by default pastes the contents of the primary buffer at the pointer's position. Many users of two-button mice emulate a three-button mouse by clicking both the right and left buttons simultaneously.
Common mice have a wheel with a detent ("bumpy" feel) to keep it from drifting accidentally; this wheel also has an optical encoder like those for the ball; it's typically used to scroll a tall window vertically. However, many such scroll wheels are mounted in a little internal spring-loaded frame so that simply pushing down on them makes them work as a third button.
The scroll wheel, a notably different form of mouse-button, consists of a small wheel that the user can rotate to provide immediate one-dimensional input. Usually, this input translates into "scrolling" up or down within the active window or GUI-element. The wheel is often – but not always – engineered with a detent to turn in short steps, rather than continuously, to allow the operator to more easily intuit how far they are scrolling. The scroll wheel nearly always includes a third (center) button, activated by pushing the wheel down into the mouse.
The scroll wheel can provide convenience, especially when navigating a long document. In conjunction with the control key (Ctrl), the mouse wheel may often be used for zooming in and out; applications that support this feature include Adobe Reader, Microsoft Word, Internet Explorer, Opera, Mozilla Firefox and Mulberry, and in Mac OS X, holding the control key while scrolling zooms in on the entire screen. Some applications also allow the user to scroll left and right by pressing the shift key while using the mouse wheel.
KYE Systems introduced the first mouse with top scroll wheel in 1995, marketed as the Genius EasyScroll and Mouse Systems ProAgio mouse. However, mainstream adoption of the scroll wheel mouse did not occur until Microsoft released the Microsoft IntelliMouse in 1996. It became a commercial success in 1997 when their Microsoft Office application suite and their Internet Explorer browser started supporting its wheel-scrolling feature. Since then the scroll wheel has become a standard feature of many mouse models.
Some mouse models have two wheels, or wheels that can be moved sideways (such as the MX Revolution), separately assigned to horizontal and vertical scrolling. Designs exist which make use of a "rocker" button instead of a wheel – a pivoting button that a user can press at the top or bottom, simulating "up" and "down" respectively. A peculiar early example was a mouse by Saitek which had a joystick-style hatswitch on it.
A more recent form of mouse wheel is the tilt-wheel. Tilt wheels are essentially conventional mouse wheels that have been modified with a pair of sensors articulated to the tilting mechanism. These sensors are mapped, by default, to horizontal scrolling.
A third variety of built-in scrolling device, the scroll ball, essentially consists of a trackball embedded in the upper surface of the mouse. The user can scroll in all possible directions in very much the same way as with the actual mouse, and in some mice, can use it as a trackball. Mice featuring a scroll ball include Apple's Mighty Mouse and the IOGEAR 4D Web Cruiser Optical Scroll Ball Mouse. IBM's ergonomics laboratory designed a mouse with a pointing stick in it, envisioned to be used for scrolling, zooming or (with appropriate software) controlling a second pointer.
Operating system use
The Macintosh user interface, by design, always has and still does make all functions available with a single-button mouse. Apple's Human Interface Guidelines still specify that all software-providers need to make functions available with a single button mouse. Context menus are available using the Control Key ^ Ctrl.
The original Mac OS assumed a one-button mouse. While there has long been an aftermarket for mice with two, three, or more buttons, and extensive configurable support to complement such devices in all major software packages on the platform, Mac OS X shipped with hardcoded support for multi-button mice. X Window System applications, which Mac OS X can also run, have been developed with the use of two-button or even three-button mice in mind.
Advocates of multiple-button mice argue that support for a single-button mouse often leads to clumsy workarounds in interfaces where a given object may have more than one appropriate action. One workaround was the double click, first used on the Apple Lisa, to allow both the "select" and "open" operation to be performed with a single button. Several common workarounds exist, and some are specified by the Apple Human Interface Guidelines.
One such workaround (that favored on Apple platforms) has the user hold down one or more keys on the keyboard before pressing the mouse button (typically control on a Macintosh for contextual menus). This has the disadvantage that it requires that both the user's hands be engaged. It also requires that the user perform actions on completely separate devices in concert; that is, holding a key on the keyboard while pressing a button on the mouse. This can be a difficult task for a disabled user, although can be remedied by allowing keys to stick so that they do not need to be pressed down.
Another involves the press-and-hold technique. In a press-and-hold, the user presses and holds the single button. After a certain period, software perceives the button press not as a single click but as a separate action. This has two drawbacks: first, a slow user may press-and-hold inadvertently. Second, the user must wait for the software to detect the click as a press-and-hold, otherwise the system might interpret the button-depression as a single click. Furthermore, the remedies for these two drawbacks conflict with each other: the longer the lag time, the more the user must wait; and the shorter the lag time, the more likely it becomes that some user will accidentally press-and-hold when meaning to click. Studies have found all of the above workarounds less usable than additional mouse buttons for experienced users.
While historically, most PC mice provided two or three buttons, only the primary button was standardized in use for MS-DOS and versions of Windows through 3.1x; support and functionality for additional buttons was application specific. However, in 1992, Borland released Quattro Pro for Windows (QPW), which used the right (or secondary) mouse button to bring up a context menu for the screen object clicked (an innovation previously used on the Xerox Alto, but new to most users). Borland actively promoted the feature, advertising QPW as "The right choice", and the innovation was widely hailed as intuitive and simple. Other applications quickly followed suit, and the "right-click for properties" gesture was cemented as standard Windows UI behavior after it was implemented throughout Windows 95.
Most machines running Unix or a Unix-like operating system run the X Window System which almost always encourages a three-button mouse. X numbers the buttons by convention. This allows user instructions to apply to mice or pointing devices that do not use conventional button placement. For example, a left-handed user may reverse the buttons, usually with a software setting. With non-conventional button placement, user directions that say "left mouse button" or "right mouse button" are confusing. The ground-breaking Xerox Parc Alto and Dorado computers from the mid-1970s used three-button mice, and each button was assigned a color. Red was used for the left (or primary) button, yellow for the middle (secondary), and blue for the right (meta or tertiary). This naming convention lives on in some Smalltalk environments, such as Squeak, and can be less confusing than the right, middle and left designations.
Acorn's RISC OS based computers necessarily use all three mouse buttons throughout their WIMP based GUI. RISC OS refers to the three buttons (from left to right) as
Select functions in the same way as the "Primary" mouse button in other operating systems.
Menu will bring up a context-sensitive menu appropriate for the position of the pointer, and this often provides the only means of activating this menu. This menu in most applications equates to the "Application Menu" found at the top of the screen in Mac OS, and underneath the window title under Microsoft Windows.
Adjust serves for selecting multiple items in the "Filer" desktop, and for altering parameters of objects within applications – although its exact function usually depends on the programmer.
- Joe Kissell (October 7, 2004, updated 2006). "The Evolution of Scrolling: Reinventing the wheel". Interesting Thing of the Day. Retrieved 2010-02-12.
- "TrackPoint Mouse".
- "Navigator 525 Laser Mouse".