Scroll Lock

Scroll lock is a key (often with an associated status light) on most modern computer keyboards. The key is not frequently used.

The scroll lock key locks all scrolling techniques and is a remnant from the original IBM PC keyboard. In the original design, scroll lock was intended to modify the behavior of the arrow keys. When the scroll lock mode was on, the arrow keys would scroll the contents of a text window instead of moving the cursor. In this usage, scroll lock is a modifier key like Alt and Shift (which modify the function of other keys) and, more specifically, a toggling lock key like Num Lock or Caps Lock, which have a state that persists after the key is released.

Today, this particular use of scroll lock is rare. Only a few modern programs still honor this behavior, such as Microsoft Excel (in the behavior of arrows — when scroll lock is on, the selection does not move), Lotus Notes, Forté Agent, and FL Studio. In modern GUI environments, scrolling is usually accomplished using means such as scrollbars or scroll wheels. Therefore scroll lock can be regarded as a defunct feature in almost all modern programs and operating systems. Some keyboards lack scroll lock altogether. Scroll lock has fallen into such extremely infrequent use that some of the lighter-weight Linux desktop environments, such as Xfce, don't support it at all.

Other uses

• In Linux virtual consoles, the scroll lock key is used to pause screen output. This behavior emulates the Hold Screen key or similar flow control mechanisms on computer terminals. Because of this emulation, the term scroll lock is sometimes used to generically refer to a screen pausing behavior. This usage could potentially cause confusion since screen pausing behavior is not intrinsically a part of the scroll lock key. In DOS, the Pause key pauses the screen output.

• In the Opera web browser the scroll lock key plays an important role in voice recognition.

• KVM switches often use the scroll lock key with a number as a hot key to activate a softswitch for changing between channels. Similarly, the KVM-like software solution Synergy uses scroll lock to keep the keyboard and mouse control within the current screen. Some two-computer KVM switches provide that a "double click" of the scroll lock key (striking the key twice quickly) is used to switch between computers.

• In the multilingual text editor iLeap, the scroll lock key is used as a toggle switch to change between two languages.

• In Windows NT-based operating systems with a certain registry setting called "CrashOnCtrlScroll" enabled, double tapping scroll lock while holding Ctrl key initiates a system crash to allow debugging the current state of the operating system.

• In FreeBSD, and other BSD descendants, Scroll Lock still functions similarly to IBM's original design.

• Apple Keyboards do not have a scroll lock key, except for some ADB keyboards.

• On some Dell laptops the scroll lock key becomes the Fn key when an external keyboard is used. This behavior can be disabled in the BIOS.

• Individual applications may assign any function to this key as an added convenience hotkey.

• Xfire, a chat application for use while playing a video game, is activated by using the default key combination of "scroll lock" + "X". Xfire also uses Scroll lock for other in-game purposes, such as taking screenshots. Sometimes its LED is used to notify users that an event occurred.

• Pressing any Control key and the Scroll Lock key performs a Control-Break in addition to pressing the Control Key and Break (Pause) key.

• In the media system My Media System, navigation is done in a fashion very similar to the original idea of the scroll lock key. At the beginning and end of a list, navigating will move the cursor but not the view. At the middle of the list, the cursor will be locked at the middle of the screen while the view moves.

• Konsole, a terminal emulator for KDE uses the scroll lock key to make the arrow keys scroll back the buffer, rather than going up and down in the command history (the default behavior of the arrow keys in Konsole). This has often lead to problems while using the Xine media player, as Xine emits a scroll lock key signal to prevent the screensaver from starting. This will in turn make Konsole switch the arrow key behavior.

• Combat Arms, a Free-to-play Microtransaction based first person shooter, uses the scroll lock key to lock the movement of chat messages.

• Many programs (e.g. E-mail clients) will toggle the scroll lock and in the process flash the LED on and off to alert the user's attention.

See also

• SysRq

External links

• Straightdope article about the scroll lock key

IBM PC keyboard (Windows, ANSI US layout)
Esc		F1	F2	F3	F4		F5	F6	F7	F8		F9	F10	F11	F12		PrtScn/ SysRq	Scroll Lock	Pause/ Break
																	Insert	Home	PgUp		Num Lock	∕	∗	−
																	Delete	End	PgDn		7	8	9	+
																					4	5	6
																		↑			1	2	3	Enter
																	←	↓	→		0    Ins		.  Del