Release Notes for Safari Technology Preview 83

Safari Technology Preview Release 83 is now available for download for macOS Mojave and macOS High Sierra. If you already have Safari Technology Preview installed, you can update in the Software Update pane of System Preferences on macOS Mojave and from the Mac App Store’s Updates tab on macOS High Sierra. After updating to macOS Mojave, you may have to reinstall Safari Technology Preview.

This release covers WebKit revisions 245007-245618.

Web Authentication

  • Enabled WebAuthN by default on macOS (r245589)
  • Changed to cancel the pending request when a new request is made (r245043)
  • Changed to return InvalidStateError to sites whenever authenticators return such error (r245262)

Pointer Events

  • Fixed isPrimary property of pointercancel events to match previous events for that pointer (r245020)
  • Fixed calling preventDefault() on pointerdown to prevent “compatibility” mouse events (r245585)

Storage Access API

  • Changed to only consume the user gesture when the user explicitly denies access and made document.hasStorageAccess() return true when the feature is off (r245025)


  • Implemented backing-sharing in compositing layers, allowing overlap layers to paint into the backing store of another layer (r245170)
  • Changed layers painting into shared backing to contribute to overlap (r245502)
  • Changed to repaint when the set of backing-sharing layers changes (r245220)
  • Fixed rendering of backing-sharing layers with transforms (r245205)
  • Fixed layer bounds for sharing layers that paint with transforms (r245208)
  • Fixed layer-related flashing with composited overflow: scroll (r245602)
  • Fixed overflow: scroll that becomes non-scrollable to stop being composited (r245212)
  • Fixed content disappearing when the scroller hosting a shared layer becomes non-scrollable (r245206)
  • Fixed rendering issues when layer contents become non-opaque (r245207)

Service Workers

  • Changed to terminate a service worker instance when its SWServer is destroyed (r245200)
  • Changed a service worker process to app nap when all of its clients app nap (r245299)


  • Implemented line-break: anywhere (r245275)
  • Implemented a modern “clearfix” with display: flow-root (r245494)
  • Implemented page-break-* and -webkit-column-break-* as legacy-shorthands. (r245276)
  • Fixed font-optical-sizing applying the wrong variation value (r245598)
  • Updated CSS grid when changing auto repeat type (r245295)
  • Updated to use max size to compute auto repeat CSS grid tracks (r245279)


  • Defined a media buffering policy (r245039)
  • Allowed sequential playback of media files when initial playback started with a user gesture (r245467)
  • Fixed video stream freezing when the front camera orientation changes (r245033)


  • Fixed the in-view center point for elements larger than the viewport (r245320)


  • Changed to preserve DOM selection after clicking a button that hides itself on mousedown (r245238)
  • Limited the number of prefetches of a given page (r245171)

Web Inspector

  • Changed the user gesture toggle to also force a user interaction flag (r245366)
  • Fixed the colors in the network table waterfall container for Dark Mode (r245484)
  • Fixed context menu items in the DOM tree when not clicking directly on the node representation in the Elements tab (r245495)
  • Fixed Storage tab crashes when adding new local storage or session storage entries (r245535)
  • Fixed the CPU timeline and Memory timeline bars sometimes incorrectly drawing and jumping around while scrolling (r245498)
  • Made it easier to switch to a DOM node in the Elements tab from a returned DOM node in the Audit tab (r245497)