How to Change Firefox Mouse Wheel Scroll Speed?

Xah Lee, 2011-05-30, …, 2012-04-24

Adjust Mouse Wheel Scroll Speed

1. In the URL field, type about:config.
2. Scroll down to mousewheel.withnokey.sysnumlines. Double-click the line to set the value to “false”.
3. Double-click the line mousewheel.withnokey.numlines, and set it to a number you like.

The change is immediate. You don't need to restart Firefox. This works in Linux too.

Set Mouse Wheel to Page Up/Down

1. Click on mousewheel.withnokey.action line.
2. Set the value to 1.

Turn on AutoScroll in Firefox Linux

To turn on autoscroll feature on Linux:

1. Paste about:config in the URL field.
2. Double click to set general.autoScroll to true.

This lets you middle-click on a empty area to pan-scroll in any direction by moving mouse.

Tech Detail

The mousewheel variables has these 2 forms:

• mousewheel.‹modifier key›.‹type›
• mousewheel.horizscroll.‹modifier key›.‹type›

The ‹modifier key› key is one of: withnokey, withaltkey, withcontrolkey, withshiftkey, withmetakey.

The ‹type› is one of: action, numlines, sysnumlines.

Possible Action Values

The important part is the values for the action. The action code determines whether you are scrolling by pixels, lines, pages, etc. Here are the possible values and meaning:

• 0 - Scroll document by a number of lines (given by the numlines property)
• 1 - Scroll document by one page
• 2 - Move back/forward in history
• 3 - Make text larger/smaller
• 4 - Scroll document by a number of pixels (given by the numlines property)

numlines

Number of lines to scroll by if action is set to value 0, or pixels if action is set to value 4; otherwise, this value is ignored.

sysnumlines

Use system preferences to determine how many lines to scroll by.

Reference

Source kb.mozillazine.org