A quick and easy way to render HTML text with the body of a Flex Alert box. There is no API to set the htmlText property of the Alert text field, but you can access it using the mx_internal namespace.
var title:String ="HTML Alert!";
var htmlBody:String = "This is my HTML message with <b>Bold</b> text and <br/> HTML formatting <b/>";
var alert:Alert = Alert.show(str, htmlBody); // now target the Alert text field (after we have opened it) and set the HTML text property
use namespace mx.core.mx_internal;
IUITextField(alert.alertForm.textField).htmlText = htmlBody;