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title: Pebble SDK 4.0-beta17 - Changelog
date: 2016-08-16
---

This is a developer preview release of SDK 4.0. No firmware is provided.

### Changes to Firmware

* Added support for [running developer apps written in JavaScript](/blog/2016/08/15/introducing-rockyjs-watchfaces/)

### Changes to SDK

* AppGlance icons must now be provided as references to `publishedMedia`
  in package.json. Providing plain resource IDs will not work.
* Custom timeline icons can now be created via `publishedMedia`.
* Added support initial for building JavaScript apps. These apps won't
  support aplite.

### Known Issues

* `publishedMedia` is completely undocumented. Updated documentation will
  be available soon. In the interim, continue using 4.0-dp3 to develop
  appglances.