Platform/Layout

About

The Platform Layout Team is primarily responsible for Gecko's style system and layout engine. We strive to build and maintain an engine that is both high-performance and standards-compliant, while providing support for features unique to Firefox.

The team's technical domains within Gecko include:

• CSS animations and transitions
• CSS parsing and computation
• Layout (of all types, including block and inline, positioned, columns, floats, flexbox, grid, form controls, images, video, tables, and text)
• Printing
• SVG
• Fonts and Typography

Contact Information

• Matrix/Riot.IM: #layout on chat.mozilla.org
• E-mail: Subscribe to dev-platform@lists.mozilla.org

Communications Channel Guidelines

• Synchronous discussions about engineering-specific topics (bugs, patches, code reviews, architectural issues, etc.) should happen in #layout on chat.mozilla.org.

Roadmap and Status

Kanban Board

Our Bugzilla kanban board is a quick way to find out what bug fixes and enhancements are upcoming or in progress.

Standup Notes

For very detailed information, notes from the team's weekly standup meetings are available.
For standup notes prior to 2024, please see the Layout Archive

Release Notes

We publish notes and lists of all fixed layout bugs for a given release. These release notes call out items of particular importance (new features, webcompat fixes) that may be helpful for web content authors.

Bugs and Triage

Filing a Bug

Open a bug under "Product: Core", using one of the following components:

• CSS Parsing and Computation
• CSS Transitions and Animations
• DOM: CSS Object Model
• Layout
• Layout: Block and Inline
• Layout: Columns
• Layout: Flexbox
• Layout: Floats
• Layout: Form
• Layout: Generated Content, Lists, and Counters
• Layout: Grid
• Layout: Images, Video, and HTML Frames
• Layout: Positioned
• Layout: Ruby
• Layout: Scrolling and Overflow
• Layout: Tables
• Layout: Text and Fonts
• Print Preview
• Printing: Output
• Printing: Setup
• SVG

Triage Process & Guidelines

If you're curious about how we triage and prioritize bugs, please visit our triage page for more information. This page includes information about our triage process and guidelines, as well as useful triage and backlog related bug queries.

Whiteboard Tags

We use the following strings (tags) in the whiteboard field on bugs in Bugzilla to track important metadata:

• [layout:backlog]: Indicates the bug is in our backlog, and is either under active development, or planned development for the current year (see bug priority for approximate timeline).
• [layout:icebox]: Indicates a bug we are considering including in our backlog in the future, but are unlikely to work on in the current year.
• [layout:triage-discuss]: Indicates that we plan to discuss this bug in more detail at one of our internal, bi-weekly triage meetings. Usually this is set if the severity level is disputed, or in question, or other triage details of the bug are unclear.

Contributing

We always welcome new contributors! Here are a few things you can do to get started:

• Read through the Firefox docs, particularly the Firefox Contributor's Quick Reference Guide.
• Follow the instructions for building Firefox.
• Read the programmer's primer on Gecko, particularly the layout section.
• Get familiar with the Mozilla code style guidelines.

Starter Bugs

If you're looking for a good first bug to fix, the following resources may help:

• Simple layout bugs on Bugs Ahoy!
• Layout bugs marked as "good-first-bug" on Bugzilla