Opera 12.00

# Improvements
* General and User Interface
- A custom user agent preference has been added to opera:config
* Display and Scripting
- Improved pipelining, JavaScript, and Turbo
# Fixes and Stability Enhancements
* General and User Interface
- Fixed an issue with missing region definitions for some regions
- Fixed UI artifacts in viewport when scrolling a page containing a fixed element with 100% height
- Fixed an issue with the tab bar
- Resolved an issue where hovering the close button in an inactive tab would steal its hover state, instead of propagating it
- Fixed incorrect address bar focus and update behavior
- Fixed an issue where search suggestion latency could provide incorrect suggestions under certain conditions
- Cancelling address field dropdown now reverts it to its previous state
- Fixed several minor issues with browser history
- Fixed an issue with Speed Dial entries not updating under certain conditions
* Display and Scripting
- Behvior improvements and enhancements to HTML5 Drag and Drop
- Fixed Canvas clearRect behavior
- Resolved an issue where XMLHttpRequest.status becomes 0 instead of 401 or 407 on cached response
- Fixed artifacts in WebM videos
- Fixed an issue with scripts saturating setInterval()
- Corrected responseXML's null behavior
- Fixed incorrect behavior with window.close and a user-initiated event
- Resolved an issue where clearTimeout() would not remove timeout
- Fixed a clipping error when combining CSS transforms and opacity
- Fixed some issues with painting and repainting that could occur under certain conditions
- Fixed an issue with drag and drop resource usage
* Mail, News, Chat
- Fixed an issue with long attachment names preventing some UI elements from showing properly
* Network and Site-Specific
- Resolved some issues with Google sites
- Resolved an issue that caused some third-party login systems to fail under certain conditions
- Fixed an issue with HTTPS connections and proxies
* Security
- Fixed an issue where hidden keyboard navigation could allow cross site scripting or code execution
- Fixed an issue where a combination of clicks and key presses could lead to cross site scripting or code execution
- Fixed an issue where cross-domain JSON resources may be exposed as JavaScript variable data
- Fixed an issue where carefully timed reloads, redirects, and navigation could spoof the address field
- Fixed an issue where pages could prevent navigation to a target page, spoofing the address field