Specs: Change event model to support default return values. Change

sky/specs/events.md

Index: sky/specs/events.md
diff --git a/sky/specs/events.md b/sky/specs/events.md
index 1ae7492f895235cadb4b5d9a8108629b2b136efc..8e49acced3bb974e0b2930fa13bebd0da7e60406 100644
--- a/sky/specs/events.md
+++ b/sky/specs/events.md
@@ -27,7 +27,7 @@ Sky Event Model
   //
   // The advantage of this would be the ability to enforce (or at
   // least better catch) incorrect uses of the API, e.g. to make sure
-  // people don't stop on themselves in 'pointer-down' capture.
+  // people don't stomp on themselves with the return value.
 
   callback EventListener any (Event event);
     // if the return value is not undefined:
@@ -35,8 +35,8 @@ Sky Event Model
     //   set event.handled to true
 
   abstract class EventTarget {
-    any dispatchEvent(Event event); // O(N) in total number of listeners for this type in the chain
-      // sets event.handled to false and event.result to undefined
+    any dispatchEvent(Event event, any defaultResult = null); // O(N) in total number of listeners for this type in the chain
+      // sets event.handled to false and event.result to defaultResult
       // makes a record of the event target chain by calling getEventDispatchChain()
       // invokes all the handlers on the chain in turn
       // returns event.result