Opera has posted what looks like a great new Web debugging tool Opera Dragonfly which is released in alpha.

Debug JavaScript, inspect CSS and the DOM, and view any errors – Opera Dragonfly makes developing using Opera easier than ever, both on your computer and mobile phone.

Shawn Lauriat has a nice write-up that tells the story:

It offers most of the familiar tools for DOM inspection (along with a nice DOM editing capability), error logging (with the same granularity as before wrapped in a more polished UI), a JavaScript debugger that rivals WebKit's Drosera, a JavaScript thread logger, and a lot more that I haven't explored yet.

Time will tell whether Dragonfly can get enough developers to use Opera and keep them there, and how much the developers behind the new developer tools listen to the community in the coming iterations, but so far this looks extremely promising.

Features

• Reach breaking point step by step: Opera Dragonfly's fully featured JavaScript debugger makes building sophisticated Ajax applications easier than ever. Step through your code line by line, setting break points along the way. This allows you to make sure your application and scripts are acting as you designed them.
• Redefine your style: Its not just the DOM you can inspect. Check out what CSS rules apply to which element, and what rules are inherited or set by browser defaults. Overridden rules are highlighted so you can see what styles are or aren't applied. Support for editing CSS rules will be added in an upcoming version.
• Spot your errors: An improved error console allows you to see, filter and log any errors in your scripts, pointing to the exact position the error occurred. Use this in combination with the other tools to hunt down and fix your site’s bugs.
• Debug the DOM: View source isn’t much use if you use DOM Scripting to alter the DOM. Opera Dragonfly allows you to inspect the updated DOM and all it's properties. Support for editing the DOM will be added in an upcoming version.

The features that are not there yet, but are upcoming, include support for editing of CSS, JavaScript and the DOM, a single window mode, improved JavaScript thread handling, XHR and HTTP monitoring, improved keyboard navigation, and translation into a number of languages.

Have you checked it out? How do you like it?