Release date: April 12, 2011

Opera 11.10 is a recommended upgrade offering new and improved features plus stability enhancements.

For further reference, please see:
The previous Opera 11.10 beta for Windows changelog on the Opera changelogs website
The updated Opera version history at opera.com
New and improved features
Code name
Opera 11.10 beta uses “Barracuda” as its code name.
Opera Presto 2.8 rendering engine
Opera 11.10 beta uses the new Opera Presto 2.8 rendering engine as identified in its user agent string.
Opera/9.80 (Windows NT 5.1; U; en) Presto/2.8.131 Version/11.10
Plugin installation wizard
Enables easy installation of, for example, the Flash plug-in if it is missing from the system.
URL Filter API for Opera extensions

The URL Filter API for Opera extensions defines a DOM interface that allows extensions to add temporary rules to Opera’s native content blocker. Rules added through this API are associated with an extension and apply as long as an extension is enabled. Once an extension is disabled or the browser is shut down, the temporary rules are discarded.
It defines the API that is applied to an extension browsing context.
An extension browsing context is a browsing context that implements the Opera extension interface (opera.extension).
See: URL Filter API for Opera extensions
WebP

Opera adds support for the Google WebP image format.
This enhances Opera Turbo’s compression performance with images.
WebP is a new image format that provides lossy compression for photographic images.
A WebP file consists of VP8 image data, and a container based on the Resource Interchange File Format (RIFF).
See: WebP: A new image format for the Web
See: RIFF Container
Feature improvements
Declarative UI
Written in YAML:
A human friendly data serialization standard for all programming languages
A tool for visual layout development of YAML based CSS layouts
Improves:
Adaptation to different string sizes for different languages
Changes in layout for a specific platform to get closer to platform guidelines
Dialogs with variable contents
Feature discoverability
Subtle animations and messages have been added to improve discoverability of Opera features.
Opera Dragonfly beta 1

Opera has improved its Dragonfly debugging tool with the release of Opera Dragonfly beta 1. Opera Dragonfly covers the full debugging workflow, from inspecting network access and downloaded resources, to correcting JavaScript issues and seeing how CSS rules apply to the DOM. It supports all the newest web technologies, including SVG and HTML5 APIs such as Web Storage.
JavaScript debugger
Enables stepping through your code line by line, setting break points along the way.
Monitor the exact expression or specific variable in your JavaScript code.
Use the Break points panel to see exactly what caused a JavaScript fail.
Added new types of break points and more granular control.
CSS inspector
Check out what CSS rules apply to which element, and what rules are inherited or set by browser defaults.
Overridden rules are highlighted showing what styles are, or are not applied.
Use the CSS editing feature to edit existing properties and values.
Use the auto-complete feature to make editing faster and more convenient.
DOM inspector
Allows inspection of the updated DOM and all of its properties.
The DOM can be edited to experiment with changes directly in the browser.
Network inspector
Allows inspection of the HTTP request and response headers.
A summary of each request is shown, with the method type, response status and the time taken to be retrieved.
Drill down to see full details of each requests header.
Find latency, see how resources download and in what order, and even view cached resources.
Resource inspector
See all site resources such as images, scripts, fonts, HTML files and videos at a glance.
Storage inspector
Cookies and Web Storage can be dynamically updated, tested, inspected, and manipulated.
Error console
Allows you to see, filter and log any errors in your scripts, pointing to the exact position where the error occurred.
Use the Error console in combination with the other tools to hunt down and fix your site’s bugs.
Debug your phone or TV
Debug pages whether they are on your computer or a supported device, such as a phone running Opera Mobile 10 for Windows Mobile.
You can connect to any device running Opera Presto 2.1 or above and debug using your computer’s screen and keyboard. There is no need to struggle inputting test data with your phone’s keypad again.
Opera Widgets can also be debugged via remote debugging.
Design utilities
A color picker and a screen magnifier allow you to pick out colors from a website or widget.
The average color of an area can be selected to make it easier to pick out colors from bitmap images.
Chosen colors can be stored in a palette for later access.
Open source
Built using the open web standards you know and love, Opera Dragonfly’s source is available to view.
Not only that, but it is released on a Apache 2.0 license, meaning it is free as in freedom, as well as in beer.
Join in the project, or just check out the source code at the Opera Dragonfly repository.
Mail
Added support for phrase searching.
Improved CJK searches.
Improvements made to the panel, including a setting to disable automatic toggling.
Improved support when using the Opera Mail client with a Gmail IMAP account.
Opera now recognizes the special IMAP folders “Sent items”, “Spam”, “Trash” and treats them as equivalents of the native Sent, Spam and Trash views in Opera Mail. This also works for other IMAP servers that support the XLIST or SPECIAL-USE extensions for the IMAP specification, including the Fastmail IMAP service.
Opera now recognizes the special way in which Gmail duplicates messages that appear in the “All Mail” IMAP folder and the various folders created by Gmail’s own “labels” (including Inbox). To make the best use of this, it is recommended that you subscribe to the all the Gmail IMAP folders (this is a change from earlier advice to suggested users to unsubscribe from the [Gmail]\* folders).
Opera Mail will then make sure that messages do not show up twice in its “Unread” and “Recieved” views. As for other views like “Mailing lists”, “Contacts”, “Labels”, and “Attachments”, duplication can still occur there. You can improve on this for now by unchecking “Show hidden” for such views (use the “View” button in the mail view, then “Show > Show hidden”).
Search
Search hijacking protection: Opera now prevents third party applications from hijacking searches and other customizations in Opera.
Added a Search field to error pages, where the browser will make a search request over the net for suggestions and display them.
Speed Dial
Added Speed Dial animation to help when reordering (dragging and dropping) existing Speed Dial cells, using smooth visual cues.
Added a new “logo finder” which keys in on the main title of a page; diabled when “Reload every” is applied.
Improvements have been made to the Speed Dial flow layout.
Added the ability to set the number of Speed Dial columns (automatic by default).
Added a new dialog when adding/editing Speed Dials
It is now possible to add a custom title to Speed Dials, through the new add/edit dialog.
Sites can now reload Speed Dials automatically using one of two methods:
HTTP header: Preview-refresh: seconds
HTML code:
The Speed Dial thumbnail/icon is now determined using these criteria (in order):
Send a http header to tell the server it is a Speed Dial request
Detect big icons: and display them instead of a thumbnail
Find the important part of the page (logo), and zoom in closer
Apply CSS view-mode: minimized when generating the thumbnail
Updated graphics for Speed Dial and callout dialogs
Speed Dial now has automatic zooming
Speed Dial options are instantly applied
User JavaScript
Added support for the BeforeCSS and AfterCSS events.
See: User JavaScript: Available methods, events, and properties
Web specifications support

For your guide, Opera web specification support references are located at:
Web specifications support in Opera Presto 2.8
Web specifications support in Opera products: an overview
CSS
Gradients
Added partial support for the gradients section of the W3C CSS3 Image Values/Replaced Content module.
Using the Opera -o- vendor prefix, Opera supports:
-o-linear-gradient()
-o-repeating-linear-gradient()

A Neowin user pointed out that the beta had been uploaded to Opera’s FTP servers, which currently remains the only source to download. Opera have been known in the past for uploading builds to their FTP before official release, which could explain the quick find.

Opera 11 sports an increase in performance on top of numerous new additions including a feature many have asked for, and has finally been added; extensions. Unlike Firefox, Opera extensions can be installed and uninstalled without the need to restart the browser – a nifty little addition. Additionally the browser is capable of auto-updates of extensions which means there is no need to keep checking for updates of your extensions, you’ll be up to date at all times. Currently the extension gallery sits at 137 available extensions with the most popular being a version of Adblock called NoAds. Extensions in many browsers cannot be used in modes such as private browsing. Opera goes against this idea and support extensions in private browsing and secure connections.

With previous versions of Opera, the installer was very much a usual web browser installation process with no support of portable installation. A new installer has been implemented which as well as looking much better and being a simpler installation process, it supports portable installation options.

Google search suggestions have also been implemented making search faster and more convenient for all of its users although unfortunately, Google continue to ignore Opera by not allowing support for their most recent features such as Google Instant and Google Instant Previews.

As reported by Neowin last week, Opera was named the most secure web browser, with only six vulnerabilities being found over a period of a year. The company seems to want to keep that title by arming Opera 11 with safer address fields. The new feature gives a badge to each web page which replaces HTTP, HTTPS and opera; protocols which are only shown when focusing on the address field. By clicking on the badge it provides an overview of the security of the web page you’re visiting (e.g. If you’re on the Opera official website it will be a verified website. If you’re on a web page you’ve visited for the first time it won’t have the same verification.)

Furthermore, there is plugin on demand support which is rather like Google Chrome’s “Click to Play” extension although this feature is disabled by default. When enabled, flash content will not be loaded and needs to be clicked before it begins to load.

Last month, we were asked to guess the next Opera 11 beta feature in which flocks of people said “Hardware acceleration”. Unfortunately, that doesn’t seem to be the case but the new feature most definitely isn’t a let down.

In the end, the ability to stack tabs and a new way to pin tabs was the outcome – which are both welcomed additions. Tab stacking works by dragging a tab on top of another tab, which results in putting them into a group. From there, you can control the group by open and closing the stack with a toggle given to the last viewed web page in that group. Opera seem to be the first web browser that has implemented the ability to stack tabs which leads to the possibility that it could be a feature we soon see in Google Chrome and even Safari 6 (if we’re lucky).