Pebble SDK 4.0 - Changelog

Release Date: August 30 2016

Added the new "Diorite" platform for the Pebble 2.
Added support for writing watchfaces in JavaScript running directly on the watch using Rocky.js.
Added PBL_COMPASS, PBL_SMARTSTRAP_POWER, and PBL_PLATFORM_DIORITE defines.
Added preferred_result_display_duration to get the recommended number of milliseconds a result window should be visible before it should be closed.
Added AppExitReason and exit_reason_set for an application to be able to notify the system of the reason it is exiting.
Added AppGlanceSlice, AppGlanceResult, AppGlanceReloadSession, app_glance_add_slice, AppGlanceReloadCallback and app_glance_reload. to support AppGlances.
Added Unobstructed Area APIs: UnobstructedAreaWillChangeHandler, UnobstructedAreaChangeHandler, UnobstructedAreaDidChangeHandler, UnobstructedAreaHandlers, layer_get_unobstructed_bounds, unobstructed_area_service_subscribe and unobstructed_area_service_unsubscribe to enable a watchface to adapt to overlays partially obstructing it, such as during a Timeline Quick View.
The compass service will now return CompassStatusUnavailable on diorite watches, which do not have a compass. Apps built with SDK 2 or SDK 3 will still see CompassStatusDataInvalid.
Report memory usage for Pebble Packages at build time.
Fixed bug causing zero-length JS files to result in build failures.

pebble gdb is currently broken.
AppGlances cannot currently use system icons.
Custom AppGlance icons may not work if the assigned published media ID does not happen to also be a standard resource ID. This can usually be worked around by assigning published media IDs starting at 1 and counting up.
For apps not using AppGlances, the system default icon may appear instead of the app-specified menu icon if the resources defined for the app vary between platforms. This can be worked around by defining the menu icon resource before defining any resources that use the targetPlatforms attribute.