Mouse chording

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Mouse chording is the capability of performing actions when multiple mouse buttons are held down, much like a chorded keyboard.

Notice that chorded actions may require more training to learn if the pressing of one button does not provide feedback hinting that pressing another button will get a result.

One of the most popular applications of mouse chording, called rocker navigation, is found in Opera and in mouse gesture extensions of Mozilla Firefox. For example:

• Holding the left button and clicking right moves forward in browser's history.
• Holding the right button and clicking left moves backward in history.

In the X Window System, and on some laptops with integrated 2-button mice, a three button mouse can be emulated using a two button mouse by having a chorded click from both the right and left buttons be translated into a middle click.

The operating system Plan 9, Oberon and the acme development environment make heavy use of mouse chording.

• The left (button 1) selects.
• Holding the left and clicking the middle (button 2) cuts.
• Holding the left and clicking the right (button 3) pastes.

Copying is effected by holding the left, then clicking the middle and right in succession. This behavior is common to all text windows under Plan 9 but can have different capability under different contexts.

In Plan 9's acme programming environment some extensions of the basic chording principles are implemented. For example, sweeping while holding a mouse button can have these effects:

• Button 1 selects.
• Button 2 performs an action or executes a command.
• Button 3 performs search or other context-based actions.

OS/2 Presentation Manager can also use chording to copy and paste text using two buttons. However, Common User Access key combinations are more frequently used.

The Apple Mighty Mouse does not support mouse chording due to the design of the button sensors.

Applications that support mouse chording

This is an incomplete list, which may never be able to satisfy certain standards for completion. You can help by expanding it with sourced additions.

• Microstation - CAD software, uses chording to snap to elements.
• CATIA - CAD/CAM/CAE software, uses middle and left mouse button chording to zoom, pan and rotate screen representation
• Acme
• Opera
• Firefox with addons
• Blender 3D
• Plan 9 from Bell Labs
• Sketchup
• Wily
• Valve Hammer Editor
• World of Warcraft
• Grand Theft Auto: San Andreas - The weapon aiming system in the PC version of San Andreas implements mouse chording, as it requires the user to hold the right mouse button to aim while clicking or holding the left button to fire a weapon or use an item, such as a camera.
• Eve Online - Pressing both the left and right mouse buttons allows for an alternative method of camera control.
• Tom Clancy's Rainbow Six: Vegas 2 - On the PC version of the game, by default the right mouse button must be held to take cover and the left mouse button to fire a weapon.
• Celestia - Pressing both mouse buttons allows the user to adjust distance from an object.

External links

• acme manual page, describes the various chords in acme
• rio manual page, describes chording inside the Plan 9 window system
• Copying and Pasting using the Mouse, describes chording in OS/2.