Gecko 1.9 Alpha 3 introduces several new features which can be tested by using Gran Paradiso Alpha 3:

• Animated PNG (APNG) images are now supported.
• The DOM clientLeft and clientTop attributes are now supported.
• Introduced support for , which puts resources into the browser's offline cache. This allows a web application to ensure that its resources are available in the cache when the browser goes into offline mode. See Marking Resources for Offline Use for further details on offline support.
• Improved precision of layout and scaling across a wide range of screen and printer resolutions.
• Implemented cycle collection in XPCOM, which detects cases where two released objects hold one another, but neither is held by anyone else. In this scenario, both objects can safely be purged. Previously, the holds each has on the other would have prevented them from being purged.
• Added support for the HttpOnly cookie attribute, which marks a cookie as readable only by the server and not by client-side scripts.
• Added a new preference, "Warn me when web sites try to redirect or reload the page", which notifies the user when the page specifies HTTP-EQUIV=refresh.

Some of the changes in Alpha versions of Gecko 1.9 affect the web and platform compatibiltity of Gran Paradiso Alpha 3:

• Windows 95, Windows 98, and Windows ME are not supported for Gecko 1.9.
• OS X 10.2 is no longer supported, and OS X 10.3.9 or better is required.
• The non-standard JavaScript Script object is no longer supported.
• Moving DOM nodes between documents now requires a call to importNode or adoptNode as per the DOM specification.