如果我没记错的话这次的升级只不过是修正BUg而不是功能提升。

到Macromedia找了一段代码

Dreamweaver 4.01 updater release notes
The Dreamweaver 4.01 updaterfixes several problems found with Dreamweaver 4 after its release.

To use the updater, you must first purchase and install a full version of Dreamweaver 4. The 4.01 updater is available for download on the Dreamweaver Support Center.

Macintosh specific fixes
Windows specific fixes
Fixes on both Macintosh and Windows

The following is a list of problems fixed by the updater:

Macintosh-only issues
Macintosh OS 9.1
• Certain specific GIF files will no longer appear as distorted in Dreamweaver.
• Some users were unable to select text in Dreamweaver while other specific programs were running in the background

• Other minor performance issues on Mac OS 9.1 have been fixed.
• For more detailed information on the fixes for OS 9.1, refer to the TechNote: Macintosh OS 9.1 issues in Dreamweaver

Macintosh Double-byte Language Support
• Can now view double-byte characters in Dreamweaver on Macintosh OS 9 with double-byte language support installed.

Windows-only issues
Windows ME
• Dreamweaver, and other programs that make browser calls, sometimes crash when Previewing in Browser on Windows ME. This updater should resolve this problem in many cases.

Issues for both Windows and Macintosh
FTP
• FTP will now honor the ASCII or BINARY transfer mode indicated in the FTPExtensionMap.txt file. This means that .cgi and .htm files will, by default, use ASCII transfer mode.


EUC encoded templates
• Change encoding of EUC-encoded templates and update files will no longer cause corruption.

Reference
• Context Sensitivity now works if you have more than one Reference book installed.

Netscape 6
• Additional Dreamweaver support for Netscape 6. This includes Check Target Browser, and javascript Behavior updates. Specifically, behaviors now work correctly across frames in Netscape 6, Drag Layer works, as well as Set Text of Layers.
• This fix can be downloaded independently, or as a part of this updater. To download independently, go to www.macromedia.com/support/dreamweaver/downloads/.


javascript API
• Added a function dw.getNaturalSize( ) to get natural image size. The function dw.getNaturalSize( ) takes a file URL as an argument and returns an array or 2 integers (or null if the argument is not a valid local image URL).

SourceSafe Integration
• Fixes a number of issues with the current Dreamweaver integration with Visual SourceSafe (VSS). The Windows version of the updater fixes several problems with checkout, checkin, and Design Notes. The Macintosh version fixes these same problems as well as problems with the Shared Site Column feature and login dialog labels.
• This fix can be downloaded independently, or as a part of this updater. To download independently, go to www.macromedia.com/support/dreamweaver/downloads/.


WebDAV Integration
• Fixes a number of issues with the current Dreamweaver integration with WebDAV including problems with host headers, header case-sensitivity, design note encoding, use of illegal characters in connection data, port numbers, and unknown file sizes in the Site window. For more in depth explanation of these fixes, please see the TechNote: Troubleshooting WebDAV Connections.
• This fix can be downloaded independently, or as a part of this updater. To download independently, go to www.macromedia.com/support/dreamweaver/downloads/.