Beta release of Mozilla's new add-on SDK
While some of the planned APIs are still missing, the ones that have already been implemented are said to be sufficiently stable. Compared with its predecessor, version 0.9, the beta doesn't offer many outwardly visible modifications. The changes affect, for instance, the integration in Electrolysis, a technology that, similar to other browsers, executes tabs and add-ons in separate processes. Other changes affect object creation and destruction and event processing.
In a table, Mozilla developer Daniel Buchner compares the Firefox add-on APIs to those of Chrome and Safari. Unsurprisingly, Firefox leads with a coverage of almost 80% of browser functions, followed by Chrome with 70%. Safari reportedly only makes about a third of its features accessible to add-ons via APIs.