Cross-browser event handling
Sadly, while the modern set of browsers all provide excellent support for most parts of the W3C’s DOM specification, event handling is the one place where significant differences between Internet Explorer and Mozilla/Safari/Opera still exists. Microsoft are not entirely to blame for this: at the time IE 5 was released, the W3C specification for DOM events had not yet been finalised. Hopefully, IE 7 will support the specification in full in addition to maintaining backwards compatibility with previous versions of IE.
This topic is also covered in detail in Stuart’s upcoming book.