This month in Servo: tabbed browsing, Windows buffs, devtools, and more!

Servo has had several new features land in our nightly builds over the last month:

• as of 2024-07-27, basic support for show() on HTMLDialogElement (@lukewarlow, #32681)
• as of 2024-07-29, the type property on HTMLFieldSetElement (@shanehandley, #32869)
• as of 2024-07-31, we now support rendering text typed in <textarea> (@mrobinson, #32886)
• as of 2024-07-31, we now support the ‘border-image’ property (@mrobinson, #32874)
• as of 2024-08-02, unsafe-eval and wasm-unsafe-eval CSP sources (@chocolate-pie, #32893)
• as of 2024-08-04, we now support playback of WAV audio files (@Melchizedek6809, #32924)
• as of 2024-08-09, we now support the structuredClone() API (@Taym95, #32960)
• as of 2024-08-12, we now support IIRFilterNode in Web Audio (@msub2, #33001)
• as of 2024-08-13, we now support navigating through cross-origin redirects (@jdm, #32996)
• as of 2024-08-23, we now support the crypto.randomUUID() API (@webbeef, #33158)
• as of 2024-08-29, the ‘clip-path’ property, except path(), polygon(), shape(), or url() values (@chocolate-pie, #33107)

We’ve upgraded Servo to SpiderMonkey 128 (@sagudev, @jschwe, #32769, #32882, #32951, #33048), WebRender 0.65 (@mrobinson, #32930, #33073), wgpu 22.0 (@sagudev, #32827, #32873, #32981, #33209), and Rust 1.80.1 (@Hmikihiro, @sagudev, #32896, #33008).

WebXR (@msub2, #33245) and flexbox (@mrobinson, #33186) are now enabled by default, and web APIs that return promises now correctly reject the promise on failure, rather than throwing an exception (@sagudev, #32923, #32950).

To get there, we revamped our WebXR API, landing support for Gamepad (@msub2, #32860), and updates to hand input (@msub2, #32958), XRBoundedReferenceSpace (@msub2, #33176), XRFrame (@msub2, #33102), XRInputSource (@msub2, #33155), XRPose (@msub2, #33146), XRSession (@msub2, #33007, #33059), XRTargetRayMode (#33155), XRView (@msub2, #33007, #33145), and XRWebGLLayer (@msub2, #33157).

And to top it all off, you can now call makeXRCompatible() on WebGL2RenderingContext (@msub2, #33097), not just on WebGLRenderingContext.

The biggest flexbox features that landed this month are the ‘gap’ property (@Loirooriol, #32891), ‘align-content: stretch’ (@mrobinson, @Loirooriol, #32906, #32913), and the ‘start’ and ‘end’ values on ‘align-items’ and ‘align-self’ (@mrobinson, @Loirooriol, #33032), as well as basic support for ‘flex-direction: column’ and ‘column-reverse’ (@mrobinson, @Loirooriol, #33031, #33068).

‘position: relative’ is now supported on flex items (@mrobinson, #33151), ‘z-index’ always creates stacking contexts for flex items (@mrobinson, #32961), and we now give flex items and flex containers their correct intrinsic sizes (@delan, @mrobinson, @mukilan, #32854).

We’re now working on support for bidirectional text, with architectural changes to the fragment tree (@mrobinson, #33030) and ‘writing-mode’ interfaces (@mrobinson, @atbrakhi, #33082), and now partial support for the ‘unicode-bidi’ property and the dir attribute (@mrobinson, @atbrakhi, #33148). Note that the dir=auto value is not yet supported.

Beyond the engine

Servo-the-browser now has a redesigned toolbar (@Melchizedek6809, 33179) and tabbed browsing (@webbeef, @Wuelle, #33100, #33229)! This includes a slick new tab page, taking advantage of a new API that lets Servo embedders register custom protocol handlers (@webbeef, #33104).

Servo now runs better on Windows, with keyboard navigation now fixed (@crbrz, #33252), --output to PNG also fixed (@crbrz, #32914), and fixes for some font- and GPU-related bugs (@crbrz, #33045, #33177), which were causing misaligned glyphs with incorrect colors on servo.org (#32459) and duckduckgo.com (#33094), and corrupted images on wikipedia.org (#33170).

Our devtools support is becoming very capable after @eerii’s final month of work on their internship project, with Servo now supporting the HTML tree (@eerii, #32655, #32884, #32888) and the Styles and Computed panels (@eerii, #33025). Stay tuned for a more in-depth post about the Servo devtools!

Changes for Servo developers

Running servoshell immediately after building it is now several seconds faster on macOS (@mrobinson, #32928).

We now run clippy in CI (@sagudev, #33150), together with the existing tidy checks in a dedicated linting job.

Servo now has new CI runners for Windows builds (@delan, #33081), thanks to your donations, cutting Windows-only build times by 70%! We’re not stopping at Windows though, and with new runners for Linux builds just around the corner, your WPT try builds will soon be a lot faster.

We’ve been running some triage meetings to investigate GitHub issues and coordinate our work on them. The next Servo issue triage meeting is on 2 September at 10:00 UTC. For more details, see project#99.

Engine reliability

August has been a huge month for squashing crash bugs in Servo, including on real-world websites.

We’ve fixed crashes when rendering floats near tables in the HTML spec (@Wuelle, #33098), removed unnecessary explicit reflows that were causing crashes on w3schools.com (@jdm, #33067), and made the HTML parser re-entrant (@jdm, #32820, #33056, html5ever#548), fixing crashes on kilonova.ro (#32454), tweakers.net (#32744), and many other sites. Several other crashes have also been fixed:

• crashes when resizing windows with WebGL on macOS (@jdm, #33124)
• crashes when rendering text with extremely long grapheme clusters (@crbrz, #33074)
• crashes when rendering text with tabs in certain fonts (@mrobinson, #32979)
• crashes in the parser after calling window.stop() (@Taym95, #33173)
• crashes when passing some values to console.log() (@jdm, #33085)
• crashes when parsing some <img srcset> values (@NotnaKO, #32980)
• crashes when parsing some HTTP header values (@ToBinio, #32973)
• crashes when setting window.opener in certain situations (@Taym95, #33002, #33122)
• crashes when removing iframes from documents (@newmoneybigbucks, #32782)
• crashes when calling new AudioContext() with unsupported options (@Taym95, #33023)
• intermittent crashes in WRSceneBuilder when exiting Servo (@Taym95, #32897)

We’ve fixed a bunch of BorrowError crashes under SpiderMonkey GC (@jdm, #33133, #24115, #32646), and we’re now working towards preventing this class of bugs with static analysis (@jdm, #33144).

Servo no longer leaks the DOM Window object when navigating (@ede1998, @rhetenor, #32773), and servoshell now terminates abnormally when panicking on Unix (@mrobinson, #32947), ensuring web tests correctly record their test results as “CRASH”.

Donations

Thanks again for your generous support! We are now receiving 3077 USD/month (+4.1% over July) in recurring donations. This includes donations from 12 people on LFX, but we will stop accepting donations there soon — please move your recurring donations to GitHub or Open Collective.

Servo is also on thanks.dev, and already three GitHub orgs that depend on Servo are sponsoring us there. If you use Servo libraries like url, html5ever, selectors, or cssparser, signing up for thanks.dev could be a good way for you (or your employer) to give back to the community.

As always, use of these funds will be decided transparently in the Technical Steering Committee. For more details, head to our Sponsorship page.