Release schedule

Date Milestone
Thu Apr 5 2018 Feature freeze
Thu Apr 19 2018 Hard code freeze
Fri May 4 2018 SDK4.0 release
Thu May 24 2018 SDK4.1 hard code freeze
Thu Jun 7 2018 SDK4.1 bugfix release
Thu Jun 21 2018 SDK4.2 hard code freeze
Thu Jul 5 2018 SDK4.2 bugfix release
Thu Aug 2 2018 EOL

Major features


SDK4 is based on the GNOME 3.28 platform, so all of the improvements for developers since GNOME 3.26 are now available.

We have also upgraded Xapian from our custom version of 1.3 to a prerelease snapshot of 1.6. This brings in all the improvements from the last three years, as well a new database format with a smaller index size that is interoperable with other Xapian installations, and a stemmer for the Indonesian language.

We have a few new API additions to our developer platform as well.

  • DModel is a library, previously included in the platform but private, used for the data models of content stored in our databases.
  • Maxwell is a library used for embedding GTK widgets inside a WebKit web view.
  • mustache-c is an implementation of the Mustache templating engine in C.

Custom overrides

It’s now possible to customize presets beyond the variables introduced in the last release. Custom overrides allow modifying any part of a preset. For example, to use the “Thematic” preset and modify one specific part:

    shortdef: 'Navigation.SearchBox(focus-on-map: false)'
!import 'thematic'

The format is identical to that of the variables, and both can be used together but, instead of a variable name, these points are specified with a path composed of every node from the root node to the target node.

General improvements

This release saw many small improvements in the areas of visual design of the modular framework; and performance, especially in video playback and database query operations.


There’s now a walkthrough for the process of making an app with the modular framework. We’ll be adding to this guide in future bugfix releases.

Migration guide from SDK3

Some app presets were renamed:

  • “A” is now “Library
  • “B” is now “Thematic”
  • “Buffet” is now “Exploration”
  • “Escola” is now “Course”

If you were importing these presets in your app.yaml file, or their themes in your overrides.scss file, you should change the name. For up-to-date documentation on the app presets, see the presets documentation.

You will have to rebuild any databases in your app to work with the new version of Xapian.

Release notes

SDK 4.2 (July 5, 2018)

  • Modular Framework: Media content now stops playing after closing the lightbox view.
  • Modular Framework: Thematic apps can again order home page cards.
  • Modular Framework: Suggested content properly hides when leaving the article view.
  • Renderer: Links to wikihow sources are properly displayed.
  • Services: Evergreen content always shows in the Feed.
  • Services: Removed a memory leak.
  • Services: More documentation.

SDK 4.1 (June 7, 2018)

  • Services: Some bugfixes to keep apps using older SDK versions working correctly.
  • Services: Fixed a crash that could occur sometimes.
  • Documentation: Expanded the tutorial and made some minor fixes in the text.
  • Modular framework: Some visual improvements to search boxes.
  • Modular framework: Fixed a bug whereby vertical and horizontal CSS classes were not added to cards correctly.
  • Modular framework: Minor performance improvements.
  • Renderer: Fixed a bug whereby extra bullets were added to bulleted lists.

SDK 4.0 (May 4, 2018)

This is the first release in the SDK4 series.