The current syntax of the @Listen annotation is brittle: @Listen("onClick = button[label='Clear']")

I suggest this new approach:

1. Convert all events to an enum Events which implements the IEvent interface (with a single method String name()). This allows to create several such enums for custom events.
2. Split the single parameter for @Listen into two: @Listen(event=Enum, selector=String

Everywhere in the code, an IEvent should be preferred or required to avoid typos, String constants abused for value instances and similar problems.