Differences Between Dreamweaver CS4 and Dreamweaver CS3

New Workspace and User Interface:
Dreamweaver CS3 for Windows brought in the idea of different program layouts depending upon what type of Web designer or developer you were. Dreamweaver CS4 takes that to a new level. There are 8 default layouts including: App Developer, App Developer Plus, Classic, Coder, Coder Plus, Designer, Designer Compact, and Dual Screen. And if that's not enough, you can now define your own, or simply modify an existing one to match exactly what you need it to do. And it no longer matters if you're on a Mac or not - these features are in both Windows and Macintosh versions of Dreamweaver CS4.

Live View of Your Pages:
If you've ever tried to edit a dynamic or data-driven site in Dreamweaver, you know how frustrating that can be. Just hitting the preview button forces you to publish to your "testing server", which for many of us is our live site. But now, Dreamweaver CS4 can preview pages in "live mode" with interactivity and dynamic elements included. It can even load data sources so you can see how those will impact the page. Plus, you can move through JavaScript scripts and stop the script just where you need to work on a design element, giving you much more control over over the design and interactivity as a whole.

Improved CSS Support:
There is a CSS properties navigator as well as the HTML properties that we're used to. These give you greater control over the style properties including creating style rules for exactly the site section you're in. You can then dial back the specificity to however specific or general you need for your CSS document. You can evaluate what CSS styles are impacting areas of your pages. You simply highlight the area that you're not sure of, and alt- or option-click and Dreamweaver CS4 tells you which styles are affecting it. Then you can edit them by clicking on them and they'll open in another window in Dreamweaver.

Photoshop Smart Objects:
With Dreamweaver CS3 you could import images directly from Photoshop, but in CS4, they take that a step further. Now when you drag a Photoshop (PSD) image into Dreamweaver, it creates a "smart object". This generates an optimized Web image ready for you to use in your pages. If you resize the image in Dreamweaver, you can then get an optimized copy of the image at that size. Plus, if you make changes to the original image, they can be reflected into the Web document.

HTML Data Sets and Suggestions for Use:
In Dreamweaver CS3, you could load XML and database data sets into your documents, but once you had them loaded, you had to figure out what to do with them. Dreamweaver CS4 provides some of the more common uses as well as the ability to load HTML pages (with repeating elements) as your data sets.

Subversion Integration:
Dreamweaver CS4 has basic check-in and check-out functionality, like previous versions. But now it integrates with the third-party application Subversion to provide powerful version control and rollback functionality for your Dreamweaver websites.

Author Adobe AIR Applications:
Dreamweaver CS4 now comes with an extension to allow you to author Adobe AIR applications from right within Dreamweaver.

Deprecated Features:
The following features are no longer in Dreamweaver CS4:

* Timelines
* Web services
* Layout mode
* Site Map view
* Java Bean support
* Flash elements (Image Viewer)
* Flash text and Flash buttons
* ASP.NET and JSP server behaviors and recordsets

Source: http://webdesign.about.com/od/dreamweaver/p/diff_dw_cs4_cs3.htm

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Adobe Dreamweaver CS4

Live View
Design your web pages under real-world browser conditions with the new Live View in Adobe® Dreamweaver® CS4 — while still retaining direct access to the code. Changes to the code are instantly reflected in the rendered display.

Code hinting for Ajax and JavaScript frameworks
Write JavaScript more efficiently with improved support for JavaScript core objects and primitive data types. Put the extended coding functionality of Dreamweaver CS4 to work by incorporating popular JavaScript frameworks, including jQuery, Prototype, and Spry.
New user interface
Work faster and smarter across Adobe Creative Suite® 4 components with a shared user interface design. Toggle quickly from one work environment to the next with the workspace switcher.

Related Files and Code Navigator
Click any included file shown in the Related Files bar to see both its source in Code view and the parent page in Design view. The new Code Navigator feature shows you the CSS source code that affects your current selection and allows you to access it quickly.

HTML data sets
Integrate the power of dynamic data into your web pages without the learning curve of mastering databases or XML coding. Spry Data Sets recognize content in a simple HTML table as an interactive data source.

Adobe InContext Editing (Free preview)
Design your pages in Dreamweaver so end users can edit their web pages without help from you or additional software using the Adobe InContext Editing online service. As a Dreamweaver designer, you can limit changes to specific pages, distinct regions, and even custom formatting options.

Adobe Photoshop Smart Objects
Insert any Adobe Photoshop® PSD document in Dreamweaver to create an image Smart Object tightly linked to the source file. Make changes to the source image, and update your image in Dreamweaver without opening Photoshop.

CSS best practices
Implement CSS best practices without writing code. Create new CSS rules in the Properties panel, and get clear, simple explanations of where each property fits in the cascade of styles.

Subversion integration
Update your site and check in modifications directly from within Dreamweaver. Dreamweaver CS4 integrates with Subversion® software, an open source versioning control system, for a more robust check-in/check-out experience.

Adobe AIR authoring support
Create HTML and JavaScript based Adobe AIR™ applications directly within Dreamweaver. Preview AIR applications without leaving Dreamweaver. Get your Adobe AIR application ready to deploy with AIR packaging and code-signing features.

Source: http://www.adobe.com/products/dreamweaver/features/?view=topnew

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