A common user interaction is the humble MessageBox. Doing a quick web search of “silverlight messagebox” tends to produce a number of results lamenting how MessageBox is not available in Silverlight, and discussing various techniques to simulate a MessageBox.

While it’s true that there wasn’t a MessageBox until the Release Candidate, there IS a MessageBox class in the final (RTW, Release To Web) version of Silverlight 2.0!

It’s System.Windows.MessageBox. It’s a bit limited:

• It doesn’t display an icon on Windows (although according to the docs, the Macintosh version does display an icon!)
• It offers a choice of a single button called OK or two buttons: OK and Cancel.

One nice part of the MessageBox is that it allows customization of the title bar text (unlike the Javascript alert() and confirm() dialogs). And it’s a bit less code than other alternatives, and it’s more visually consistent across various browsers than the Javascript alternatives. Here’s the code to generate a MessageBox with all the options:

MessageBox.Show("This is the messageBoxText",
                "This is the caption", 
                MessageBoxButton.OKCancel);

This renders like this on Windows Vista:

If you only want the OK button, just pass MessageBoxButton.OK as the last parameter:

Finally, there’s a simpler overload that only takes the messageBoxText:

MessageBox.Show("This is the messageBoxText");

This generates a MessageBox with only the OK button and no text in the title bar:

In addition, the Show method returns a MessageBoxResult, which has the following values: OK, Yes, No, Cancel, None. According to the docs, the Yes, No, and None values are currently unused. (This makes sense, as there are only OK and Cancel buttons.)

Here’s a link to the documentation: http://msdn.microsoft.com/en-us/library/system.windows.messagebox(VS.95).aspx