Release Notes for Safari Technology Preview 75

Safari Technology Preview Release 75 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 239991-240780.


  • Enabled Screen Capture (r240635)
  • Updated track sources to be unmuted whenever re-enabled after setDirection changes (r240152)
  • Updated Screen Capture to correctly handle rotation for local video playback (r240000)

Intelligent Tracking Prevention

  • Added the ability to enable and disable Intelligent Tracking Prevention Debug Mode in the Develop menu (r240129)

Web Authentication

  • Changed the nonce in the CTAP kInit command to weak random values (r240081, r240103)


  • Allowed <video> elements not in the DOM to AirPlay (r240537)


  • Added support for returning relative frames for accessibility (r240219)
  • Changed the AXSelected attribute on RadioButton to not be settable (r240205)


  • Fixed the position of layers nested inside of composited overflow-scroll (r240271)
  • Updated animations to only trigger layer re-compositing when necessary (r240012)


  • Implemented PerformanceObserver.supportedEntryTypes (r240454)
  • Fixed a bug where sendBeacon to a previously-unvisited HTTPS domain would always fail (r240094)
  • Improved Fetch data: URL handling to align with standards (r240706)


  • Added support for running subtests (r240649)
  • Added support for simulating single touches to Automation.performInteractionSequence (r240554)
  • Updated Automation.computeElementLayout to return Visual Viewport-aware coordinates (r240195)
  • Updated POST commands to require a valid parameters object (r240648)

Web Inspector

  • Added Changes sidebar panel to Elements tab (r240559, 240699)
  • Added support for CSS Color 4 color syntaxes (r240550)
  • Added supports key to test/group for compatibility in the Audit tab (r240469)
  • Added a mechanism for Web Inspector to edit page settings on a remote target (r240540)
  • Added a mechanism for Web Inspector to edit page WebRTC settings on a remote target (r240644, r240664)
  • Added a mechanism for Web Inspector to edit the user agent of a remote target (r240549)
  • Added grouped CSS rules by resource to the Changes sidebar panel (r240741)
  • Added a CPU usage timeline in the Timelines tab (r240457)
  • Added new mechanisms for getting related Accessibility nodes and properties for a given node for audits in the Audit tab (r240277, r240309)
  • Changed the style of the device settings override popover content (r240737)
  • Changed the Elements tab to toggle visibility for all selected nodes (r240639)
  • Enabled computed style cascades by default in the Styles sidebar (r240691)
  • Excluded Debugger Threads from CPU usage values in Web Inspector (r240522)
  • FIxed a bug that prevented audits from being imported in the Audit tab (r240538)
  • Improved Dark Mode appearance within Memory timeline (r240518)
  • Improved invalid Audit and Recording JSON error messages (r240471)
  • Updated the Memory Timeline View to be responsive when resizing (r240763)
  • Updated the Audit tab to ensure that each test run creates its own injected objects (r240188)
  • Updated the Network waterfall column to redraw when adding or removing new columns (r240347)
  • Updated Web Inspector to show the uncaught exception view for unhandled promise rejections (r240499)


  • Updated CSS Grid to properly handle static positions of absolute-positioned inside grid items (r240333)
  • Implemented flow-relative inset properties (r240334)
  • Implemented flow-relative margin, padding and border shorthands (r240251)
  • Changed to reject unitless length quirk in the inset shorthand (r240588)

Browser Changes

  • Removed support for the expired Do Not Track standard to prevent potential use as a fingerprinting variable.

Bug Fixes

  • Fixed snapshots removed too late after swiping back on Twitter (r240542)
  • Fixed history navigations to that were leading to a 403 HTTP error (r240750)
  • Fixed a loading hang that could occur on history navigation (r240725)
  • Updated the MIME-type parser (r240591)