Note: For more recent Dreamweaver coverage, see Bright Hub's review of Dreamweaver CS5.
In CS3, in order to preview a page in a browser on your PC without uploading to a live site, you have to make certain the testing server is set up correctly, usually in the inetpub/wwwroot folder established by Microsoft Internet Information Services. This can involve working to make the folder into a virtual directory, which depending on individual security settings can be a bit of a problem. While this is still true in CS4, the new version adds a feature called “Live View” on the design bar. This lets you see during the design phase exactly what a user would see in a browser when the site is live. This can be helpful in troubleshooting since you can see what is happening in a Javascript as it runs.
When you want to edit CSS styles in CS3 you open the CSS panel and find the particular style you want to change. This can be cumbersome. In CS4, a new option called the Code Navigator lets you place the cursor on any item on a webpage and press “Alt-Click.” This instantly opens a window that lists the external files and CSS items associated with the section. Hovering over one style opens the current properties such as size associated with that style. Pressing “Alt-Click” again opens the actual code involved.
CS4 features an enhanced method to read datasets and store data in an HTML table. It also includes a way to link external items like a Yahoo! UI calendar widget using the new Extension Manager to a Spry dataset and display it on your webpage. This is not possible in CS3. CS4 also adds four new Spry wizards to13 available in CS3. These are the Spry Validation Password, Spry Validation Confirm, Spry Validation Radio Control Group, and Spry Tooltip. CS4 drops the Spry Table.
Several other enhancements may or may not be applicable to your particular environment such as a “Related Files” view or expanded support for Javascript.