mgbrowser v0.9.17 Experimental Preview

mgbrowser v0.9.17 Experimental Preview

v0.9.17 adds modern element.style
setProperty, removeProperty and getPropertyPriority through the existing
locked Rust Stylo declaration parser and serializer. The actual DOM style
attribute remains the only retained declaration store.

Linux x86_64 / X11 or XWayland, glibc 2.35 or newer. Rust 1.91.1 and locked dependencies.

Declaration editing methods

CSS names and case-sensitive custom properties use the existing enabled grammar.
setProperty replaces both value and importance; an empty value removes even
when the supplied priority is invalid. Invalid nonempty values, unknown
properties and invalid nonempty priorities preserve the original raw attribute.
removeProperty returns the previous specified value and removes all shorthand
longhands atomically, including partial shorthands whose serialization is empty.
getPropertyPriority returns important only for an important declaration or
a shorthand whose complete set of constituents is important.

Genuine same-realm style receivers are checked before arity and argument
conversion. Conversion remains ordered and reentrant; completed inner effects
and thrown-value identity are preserved. All four style methods have stable
per-realm identity and correct public name/length metadata. Native declaration
operations do not call author-overridden methods. Reads and exact no-ops do not
rewrite raw attributes. No dependency, grammar preference, browser protocol,
worker profile or resource allowance is added.
Frozen contract.

The existing 16,384-byte declaration input/output limits include priority.
Fallible return-string and mutation admission precede DOM commit, including
removal. Ordinary Host errors remain catchable; existing VM fatal behavior
remains terminal. Parser and atom work still rely on unchanged process/System/
CPU containment, not comprehensive cooperative budgeting.

Validation and delivery evidence

Focused local checks pass all 28 public binding controls, 23 private declaration/
resource controls, three fresh restricted-child cases and one retained
Init/lifecycle/click case. Actual pre-feature missing-method failures remain
recorded. The retained case completes real separate lifecycle tasks and a later
click without renewing its cumulative source/work/System budgets. Independent
source review of the three production files found no outstanding issue.
These are authored controls, not upstream WPT passes or denominator additions.

Final-version full Rust/JSPLAN regressions pass. Complete reviewed WPT selections
retain static338 pass /611 fail /62 unsupported of1,011 and separate Window15/16
files with77/79 actual final subtests passing. No infrastructure failures,
denominator changes or weakened protections. Every static outcome, page/pixel,
relation, diagnostic, request and worker counter matches the accepted prior;
Window final inventories and the two container-unit failures remain unchanged.
Normal local package/install/updater checks and all thirteen existing native/CDP
helpers pass. Separate physical/atomic1x/2x and method-native/CDP proofs pass;
all sixteen actual screenshots were inspected. Both frozen direct-worker suites
retain all21 expected outcomes, including genuine failures/timeouts, with
confirmed owned cleanup. These are authored controls, not upstream passes.
The unchanged updater download ceiling is8 MiB. Exact-source CI/site, tagged
release and public install/update acceptance are recorded separately in the
dated work log.
Local receipts do not establish public delivery or full feature completion.

Install and known limitations

curl -fsSL https://mgbrowser.org/install.sh | bash

The installer follows the latest actually published release. It verifies
SHA-256 and installs without sudo. Checksums are not independent signatures.
Existing browser processes must restart to use an installed update.

Modern-web compatibility is poor. Google search to first result is not working.
Ordinary Playwright compatibility, full browser event-loop/testharness behavior
and React/Vue applications are not supported. Boa-backed inline and bounded
classic external scripting is enabled by default (--disable-scripts opts out);
ES modules, dynamic script loading and fetch/XHR remain unsupported. CSS, fonts,
images, tabs and resources remain bounded subsets. Length/item/indexed
enumeration, style constructors/prototypes, generic expandos, computed/rule
styles and Element.style forwarding remain deferred. These methods do not
complete CSSOM, F-003/F-005/F-016/F-026 or the formal MVP. Cookies are memory-only.
Scripted activation of empty anchors can still be rejected; the new fixture
uses ordinary text links.

Linux X11/XWayland is the GUI target. The restricted JavaScript worker is not
a sandbox for the browser as a whole: do not use this preview for banking,
sensitive authenticated browsing or arbitrary hostile websites. Existing worker
source/opcode/System-allocation/work/time/lifetime/wire and OS limits remain;
they are not whole-browser quotas or GC/RSS measurements. Fatal Boa roots may
require actual Context/worker teardown.

Project code, documentation and original artwork: Apache-2.0. Dependencies retain
their licenses in packaged THIRD_PARTY_LICENSES.txt. Published tags and assets
remain immutable.