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Support High Resolution Scrolling on Windows
Stage Shipped
Status Complete
Release target Firefox 6
Health OK
Status note Main implementation bugs point to Firefox 6 as Milestone. Please correct me if I am wrong.


Product manager Asa Dotzler
Directly Responsible Individual Alex Faaborg
Lead engineer Masayuki Nakano
Security lead `
Privacy lead `
Localization lead `
Accessibility lead `
QA lead George Carstoiu
UX lead Alex Faaborg
Product marketing lead `
Operations lead `
Additional members `

Open issues/risks


Stage 1: Definition

1. Feature overview

We need to enable users on windows to scroll with pixel level precision (when using a non-discrete wheel), similar to the fine grained level of control that users currently have on OS X. Windows Vista introduced standard mouse events that contain a higher level of scrolling precision for mouse wheel movement in 2006. Non discrete mouse wheels have been in the marketplace for awhile now, and mouse drivers are sending these events to applications.

We're doing this because:

  • Moving to pixel scrolling where possible will make a very common browser activity feel faster, more responsive, and improve the general feel of the application.

This feature falls primarily in the Experience category (from the "Discover, Experience, and Connect" vision statement.)


The goal is to scroll on Windows as well as Firefox on OS X. The fact that we only do line scrolling on windows impacts our perceived performance and responsiveness, and the general feel of the application. Scrolling is something that users do literally constantly with a Web browser (much more than any other interaction or UI control), so changes to how the application scrolls should respectively be prioritized extremely high. The fact that we don't support an important scrolling feature of Windows that was introduced 5 years ago may be indicative of just how few people at Mozilla actually use Firefox on Windows.

2. Users & use cases

"Scrolls like butter"

3. Dependencies


4. Requirements



Note that this bug is different than bug 590022. Our smooth scrolling preference simply draws 10 frames when we receive an event that the user has moved their mouse wheel a single discrete step. This project is about fine grained precision, and non-discrete mouse wheels.

Stage 2: Design

5. Functional specification


6. User experience design

Just pixel level scrolling precision, similar to scrolling in Firefox on OS X. Currently on Windows we only do line scrolling.

Stage 3: Planning

7. Implementation plan


8. Reviews

Security review


Privacy review


Localization review




Quality Assurance review


  • only applicable to Windows 7 and Windows Vista
  • drivers need to send small delta value than 1 line (or, send 1.x lines)
  • non-Logitech's user will not feel scroll smoother in default settings
  • feature should be expanded to include other mouse producers and default Windows/Linux/Mac drivers

Operations review


Stage 4: Development

9. Implementation

Stage 5: Release

10. Landing criteria

After we land the patch we need enough time for testing, since there is a wide range of mouse hardware out on the market (especially on Windows).

Feature details

Priority P1
Rank 999
Theme / Goal `
Roadmap User Experience
Secondary roadmap `
Feature list Desktop
Project `
Engineering team Desktop front-end

Team status notes

  status notes
Products ` Setting to complete since this has now landed.
Engineering ` `
Security pass `
Privacy ` `
Localization ` `
Accessibility ` `
Quality assurance Ready to land in Fx6 improvement in scrolling noticeable on Win7
User experience ` `
Product marketing ` `
Operations ` `