Difference between IsPreviewxxxxx and xxxxxxx events?

What is the difference between IsPreviewxxxxx events and xxxxx events?

Like, the IsPreviewMouseDown and MouseDown event. What is the difference in their behavior, when to use which and what a开发者_Python百科re the pitfalls in using either of them over the other.

See the MSDN here.

They're generally used to suppress handling of the corresponding actual event, particularly by parent controls. As such they're tunnelling, giving parent controls the ability to preview or reinterpret the event before the target control gets it.