Don't allow core:close event to bubble out of Pane

spec/app/pane-spec.coffee

@@ -93,11 +93,16 @@ describe "Pane", ->
         expect(editSession2.destroyed).toBeTruthy()
 
   describe "core:close", ->
-    it "removes the current item", ->
+    it "removes the current item and does not bubble the event", ->
+      containerCloseHandler = jasmine.createSpy("containerCloseHandler")
+      container.on 'core:close', containerCloseHandler
+
       initialItemCount = pane.getItems().length
       pane.trigger 'core:close'
       expect(pane.getItems().length).toBe initialItemCount - 1
 
+      expect(containerCloseHandler).not.toHaveBeenCalled()
+
   describe "pane:show-next-item and pane:show-previous-item", ->
     it "advances forward/backward through the pane's items, looping around at either end", ->
       expect(pane.currentItem).toBe view1

src/app/pane.coffee

@@ -68,6 +68,7 @@ class Pane extends View
 
   removeCurrentItem: =>
     @removeItem(@currentItem)
+    false
 
   removeItem: (item) ->
     @showNextItem() if item is @currentItem and @items.length > 1