March 18, 2012

Toggle Paint Flashing for Firefox

Paint Flashing is now in the official Release channel starting in Firefox 11. I posted a new add-on that let’s you enable Paint Flashing with one click: https://addons.mozilla.org/en-US/firefox/addon/toggle-paint-flashing/ This tool is useful for quickly inspecting how Firefox renders your web pages as it visually indicates how much screen area is being painted after the page layout is computed.The source code for the add-on is also posted.

February 7, 2012

How I got started hacking on Firefox

One of the Gecko Layout & Rendering team’s main responsibilities is the continuing development of CSS in Firefox. I recently modified the CSS style system to allow nested rule parsing. This bug fix taught me a lot about the CSS parser and how styles cascade through the rest of the Layout engine. It took me a little while to set up a dev environment, understand the bug, write tests, get the code written, reviewed, and checked in.

January 18, 2012

Firefox Invalidation

As promised, I’m going to call out Firefox Layout & Rendering code changes that my team has been working on. This bug fix from Bas Schouten (as reviewed by Robert O’Callahan) was one of those light-bulb code changes that have really advanced my understanding of the Gecko Layout Engine’s graphics code: https://bugzilla.mozilla.org/attachment.cgi?id=574190&action=diff This check-in implements “Paint Flashing”, a diagnostic tool that shows when the browser is invalidating (or repainting) a screen region that has changed.