Release Notes for Safari Technology Preview 36

Safari Technology Preview Release 36 is now available for download for macOS Sierra and betas of macOS High Sierra. If you already have Safari Technology Preview installed, you can update from the Mac App Store’s Updates tab. This release covers WebKit revisions 219131-219567.


  • Implemented Object Spread (r219443)


  • Changed to not resolve auto values of align-self and justify-self matching specification changes (r219315)
  • Fixed line-height:<number> to not be visually applied twice when text autosizing is in effect (r219543)


  • Fixed incorrect sdpMLineIndex for video to fix interoperability with Firefox (r219393)
  • Fixed sending silence data for a disabled audio track (r219524)
  • Increased the render audio buffer sizes for WebRTC (r219517)

Web Driver

  • Fixed link and partial link queries when the link contains formatting tags (r219555)


  • Disabled asynchronous image decoding for large images by default (r219438)
  • Enabled the Viewport Fit experimental feature by default (r219369)
  • Fixed an element not getting repainted when its background image finishes decoding (r219364)
  • Fixed an issue to avoid unnecessary copying of the frame buffer into a WebGL Layer (r219472)
  • Corrected the radix used in Unicode Escape in invalid character error message (r219396)
  • Fixed the low memory notification to prevent causing style recalculation (r219145)
  • Fixed GIFs with infinite animation often only playing once (r219389)


  • Fixed removing user gesture restrictions when adding the autoplay attribute to a media element during a user gesture (r219509)
  • Fixed reflecting "video" and "audio" when they are not a supported as attribute value (r219234)
  • Fixed bad behavior caused by removing samples when the presentation order does not match decode order (r219519)
  • Fixed media controls drawing behind the captions (r219558)
  • Fixed clicking the edges of media control buttons to execute the action, not just change the visual state of the button (r219549)

Web Inspector

  • Changed to group Inspector Style Sheets as part of the Stylesheets folder (r219185)
  • Improved wording for Potential Custom Element that lacks a Custom definition (r219333)
  • Fixed resources that are sometimes missing from the tree outline right before grouping into folders (r219270)
  • Fixed WebSocket resource tree elements to show the connection status (r219269)


  • Implemented name section’s module name, and skipped unknown sections (r219134)

Bug Fixes

  • Fixed the “Show My Relationship” link in (r219151)
  • Fixed an issue where font loads can cause Chinese characters to draw as .notdef (r219221)
  • Changed AppCache to ignore fallback entries whose namespace is not prefixed with the manifest path (r219272)