Tab no longer transfers focus

The tab keystroke is now suppressed in keymap
if no bindings are triggered.

Closes #258

spec/app/keymap-spec.coffee

@@ -35,8 +35,8 @@ describe "Keymap", ->
       expect(event.keystrokes).toBe 'alt-meta-x'
 
     describe "when no binding matches the event's keystroke", ->
-      it "returns true, so the event continues to propagate", ->
-        expect(keymap.handleKeyEvent(keydownEvent('0', target: fragment[0]))).toBeTruthy()
+      it "does not return false so the event continues to propagate", ->
+        expect(keymap.handleKeyEvent(keydownEvent('0', target: fragment[0]))).not.toBe false
 
     describe "when at least one binding fully matches the event's keystroke", ->
       describe "when the event's target node matches a selector with a matching binding", ->
@@ -176,8 +176,8 @@ describe "Keymap", ->
         fragment.on 'quit', quitHandler
         fragment.on 'close-other-windows', closeOtherWindowsHandler
 
-      it "only matches entire keystroke patters", ->
-        expect(keymap.handleKeyEvent(keydownEvent('c', target: fragment[0]))).toBeTruthy()
+      it "only matches entire keystroke patterns", ->
+        expect(keymap.handleKeyEvent(keydownEvent('c', target: fragment[0]))).not.toBe false
 
       describe "when the event's target node matches a selector with a partially matching multi-stroke binding", ->
         describe "when a second keystroke added to the first to match a multi-stroke binding completely", ->
@@ -197,12 +197,12 @@ describe "Keymap", ->
 
         describe "when a second keystroke added to the first doesn't match any bindings", ->
           it "clears the queued keystrokes without triggering any events", ->
-            expect(keymap.handleKeyEvent(keydownEvent('x', target: fragment[0], ctrlKey: true))).toBeFalsy()
-            expect(keymap.handleKeyEvent(keydownEvent('c', target: fragment[0]))).toBeFalsy()
+            expect(keymap.handleKeyEvent(keydownEvent('x', target: fragment[0], ctrlKey: true))).toBe false
+            expect(keymap.handleKeyEvent(keydownEvent('c', target: fragment[0]))).toBe false
             expect(quitHandler).not.toHaveBeenCalled()
             expect(closeOtherWindowsHandler).not.toHaveBeenCalled()
 
-            expect(keymap.handleKeyEvent(keydownEvent('c', target: fragment[0]))).toBeTruthy()
+            expect(keymap.handleKeyEvent(keydownEvent('c', target: fragment[0]))).not.toBe false
 
       describe "when the event's target node descends from multiple nodes that match selectors with a partial binding match", ->
         it "allows any of the bindings to be triggered upon a second keystroke, favoring the most specific selector", ->
@@ -230,6 +230,10 @@ describe "Keymap", ->
       describe "when there is a complete binding with a more specific selector", ->
         it "favors the more specific complete match", ->
 
+    describe "when a tab keystroke does not match any bindings", ->
+      it "returns false to prevent the browser from transferring focus", ->
+        expect(keymap.handleKeyEvent(keydownEvent('U+0009', target: fragment[0]))).toBe false
+
   describe ".bindKeys(selector, hash)", ->
     it "normalizes the key patterns in the hash to put the modifiers in alphabetical order", ->
       fooHandler = jasmine.createSpy('fooHandler')

src/app/keymap.coffee

@@ -70,26 +70,26 @@ class Keymap
 
     firstKeystroke = event.keystrokes.split(' ')[0]
     bindingSetsForFirstKeystroke = @bindingSetsByFirstKeystroke[firstKeystroke]
-    return true unless bindingSetsForFirstKeystroke?
+    if bindingSetsForFirstKeystroke?
+      currentNode = $(event.target)
+      currentNode = rootView if currentNode is $('body')[0]
+      while currentNode.length
+        candidateBindingSets = @bindingSetsForNode(currentNode, bindingSetsForFirstKeystroke)
+        for bindingSet in candidateBindingSets
+          command = bindingSet.commandForEvent(event)
+          if command
+            continue if @triggerCommandEvent(event, command)
+            return false
+          else if command == false
+            return false
 
-    currentNode = $(event.target)
-    currentNode = rootView if currentNode is $('body')[0]
-    while currentNode.length
-      candidateBindingSets = @bindingSetsForNode(currentNode, bindingSetsForFirstKeystroke)
-      for bindingSet in candidateBindingSets
-        command = bindingSet.commandForEvent(event)
-        if command
-          continue if @triggerCommandEvent(event, command)
-          return false
-        else if command == false
-          return false
+          if bindingSet.matchesKeystrokePrefix(event)
+            @queuedKeystrokes = event.keystrokes
+            return false
+        currentNode = currentNode.parent()
 
-        if bindingSet.matchesKeystrokePrefix(event)
-          @queuedKeystrokes = event.keystrokes
-          return false
-      currentNode = currentNode.parent()
-
-    !isMultiKeystroke
+    return false if isMultiKeystroke
+    return false if firstKeystroke is 'tab'
 
   bindingSetsForNode: (node, candidateBindingSets = @bindingSets) ->
     bindingSets = candidateBindingSets.filter (set) -> node.is(set.selector)