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Firefox 3.5 New developer features
New features for end users

Firefox 3.5 New developer features: For XUL and add-on developers

If you're an extension developer, you should start by reading Updating extensions for Firefox 3.5, which offers a helpful overview of what changes may affect your extension.

New components and functionality

Supporting private browsing mode
Firefox 3.5 offers Private Browsing mode, which doesn't record the user's activities. Extensions may support private browsing following the guidelines offered by this article.
Security changes in Firefox 3.5
This article covers security-related changes in Firefox 3.5.
Theme changes in Firefox 3.5
This article covers theme-related changes in Firefox 3.5.
Monitoring WiFi access points
Code with UniversalXPConnect privileges can now monitor the list of available access points, getting information on their SSIDs, MAC addresses, and signal strength. This can be used in tandem with Geolocation to offer WiFi-based location service.

Notable changes and improvements

* The XUL textbox widget now offers a search type, for use as search fields.
* In order to support dragging and dropping tabs between windows, the browser widget now has a swapDocShells() method.
* Added the level attribute to the panel element; this specifies whether panels appear on top of other applications, or just on top of the window the panel is contained within.
* XUL elements now support the clientHeight, clientWidth, scrollHeight, and scrollWidth properties.
* keysets now include a disabled attribute.
* In addition, keysets can now be removed using the node's removeChild() method.
* mozIStorageStatement had the initialize() method removed; consumers should use the createStatement() method instead to get a new statement object.
* The Storage API now offers support for asynchronous requests.
* The nsICookie2 interface now exposes the time at which cookies were created in its new creationTime attribute.
* Added a flag to nsIProtocolHandler (URI_IS_LOCAL_RESOURCE) that is checked during chrome registration to make sure a protocol is allowed to be registered.
* Firefox now looks for plugins in /usr/lib/mozilla/plugins on Linux, as well as the previously supported locations.
* The plugin API has been updated to include support for private browsing mode; you may now use NPN_GetValue() to query the state of private browsing mode using the variable NPNVprivateModeBool.

Introducing the future of online media! Firefox is the first browser to support open video and audio formats, allowing practically limitless new ways for sites to display rich content. The open formats also allow modern web pages to display media without requiring a plug-in or a proprietary software download.