Modes; incorporate find mode.

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/handler_stack.coffee b/lib/handler_stack.coffee
index f56683f1..764461e7 100644
--- a/lib/handler_stack.coffee
+++ b/lib/handler_stack.coffee
@@ -6,6 +6,7 @@ class HandlerStack
     @stack = []
     @counter = 0
     @passDirectlyToPage = new Object() # Used only as a constant, distinct from any other value.
+    @eventConsumed = new Object() # Used only as a constant, distinct from any other value.
 
   genId: -> @counter = ++@counter
 
@@ -32,6 +33,10 @@ class HandlerStack
         # event through to the underlying page.  The event is not suppresssed.
         if passThrough == @passDirectlyToPage
           return false
+        # If the constant @eventConsumed is returned, then discontinue further bubbling and
+        # return false.
+        if passThrough == @eventConsumed
+          return false
     true
 
   remove: (id = @currentId) ->
@@ -51,5 +56,10 @@ class HandlerStack
     handler()
     true
 
+  # Convenience wrapper for handlers which never continue propagation.
+  neverPropagate: (handler) ->
+    handler()
+    false
+
 root.HandlerStack = HandlerStack
 root.handlerStack = new HandlerStack