The imminent arrival of Windows Vista is a mixed blessing for developers. The good bit is lots of new features to play with, along with better security and an updated user interface. The downside is compatibility problems, and with the challenge of meeting expectations for well-behaved, good-looking Vista applications. There is going to be some pain.

Vista introduces a hugely expanded Windows API, some of which is also available as an add-on for Windows XP. These XP-compatible elements will be initially more interesting to developers, and include Internet Explorer 7, the XML-based GUI called XAML, the distributed computing libraries called Windows Communication Foundation, the Windows Workflow Foundation, and the XML Paper Specification. Parts of IE 7 are relevant even to FireFox diehards, particularly the RSS Platform, a centralized store for RSS feeds.

Many other parts of the new API are exclusive to Vista, including the shell and desktop APIs to support translucent glass effects, live thumbnails that show your running application in miniature, and new task dialogs that include features such as progress bars, hyperlinks and expandable text. The idea of task dialogs is to enable richer dialogs and message boxes without forcing developers to built custom forms. These are unmanaged, C++ APIs, and to use them in .NET applications you need to use Platform Invoke, which lets you call native DLLs from .NET code.

If you want your application to look like a true Vista citizen, some conditional code to call these APIs when running on Vista is the way to do it. Another handy newcomer is called Application Recovery. The idea is to enable your application to crash gracefully, saving critical data as it fails, and firing up again automatically. Apparently the feature was designed for Windows Explorer in XP, for which it works some of the time, but has now been opened up for any application. While on the subject of crashing applications, it is worth mentioning that any developer can register with Microsoft to get access to crash reports uploaded by users for their application, for the cost of a digital certificate.