RE: Event handler vs Chain of command
"Always" is a strong word. The right answer is - as usual - "it depends". :-)
CoC is usually easier and more powerful, but event handlers have some benefits too. You can have a single handler method for multiple events and you also can add handlers at runtime, not just at design-time by attributes.
It also sometimes makes sense to create a single class with handlers for various objects (such as form controls of a single form) rather then having a separate extension class for each of them.
