CompChangeEvent
@Js
class CompChangeEvent : Obj
CompChangeEvent includes details when a component slot is modified
Old value or null if adding new slot
Subject component
Name of slot modified
New value or null if removing slot
Spec of slot if defined for name (null if dynamic slot)
Comp : comp
Subject component
const Str : name
Name of slot modified
Obj? : newVal
New value or null if removing slot
Obj? : oldVal
Old value or null if adding new slot
const Spec? : slot
Spec of slot if defined for name (null if dynamic slot)