Add feature to gets DO's children recursively (optional).

starling/src/starling/display/DisplayObjectContainer.as

@@ -209,12 +209,24 @@ package starling.display
                 throw new RangeError("Invalid child index");
         }
 
-        /** Returns a child object with a certain name (non-recursively). */
-        public function getChildByName(name:String):DisplayObject
+        /** Returns a child object with a certain name. There is option to search
+         * recursively. */
+        public function getChildByName(name:String, searchInChildren:Boolean=false):DisplayObject
         {
-            var numChildren:int = mChildren.length;
-            for (var i:int=0; i<numChildren; ++i)
-                if (mChildren[i].name == name) return mChildren[i];
+            if (searchInChildren)
+            {
+                var childPath:Array = name.split(".");
+                var target:DisplayObjectContainer = this;
+                for each (var childName:String in childPath)
+                {
+                    target = target.getChildByName(childName) as DisplayObjectContainer;
+                }
+                return target;
+            } else {
+                var numChildren:int = mChildren.length;
+                for (var i:int=0; i<numChildren; ++i)
+                    if (mChildren[i].name == name) return mChildren[i];
+            }
 
             return null;
         }

tests/src/tests/display/DisplayObjectContainerTest.as

@@ -159,7 +159,41 @@ package tests.display
             child2.name = "child3";
             Assert.assertEquals(child2, parent.getChildByName("child3"));
         }
-
+
+        [Test]
+        public function testGetChildByNameRecursively():void
+        {
+            var parent:Sprite = new Sprite();
+            var child1:Sprite = new Sprite();
+            child1.name = "child1";
+
+            var child2:Sprite = new Sprite();
+            child2.name = "child2";
+
+            var child3:Sprite = new Sprite();
+            child3.name = "child3";
+
+            parent.addChild(child1);
+            child1.addChild(child2);
+            child2.addChild(child3);
+
+            Assert.assertEquals(child1, parent.getChildByName("child1", true));
+            Assert.assertEquals(child2, parent.getChildByName("child1.child2", true));
+            Assert.assertEquals(child3, parent.getChildByName("child1.child2.child3", true));
+            Assert.assertNull(parent.getChildByName("child1.child2"));
+        }
+
+        [Test(expects="TypeError")]
+        public function testGetChildByNameRecursivelyWithError():void
+        {
+            var parent:Sprite = new Sprite();
+            var child1:Sprite = new Sprite();
+            child1.name = "child1";
+
+            parent.addChild(child1);
+            parent.getChildByName("child1.child2.child3", true);
+        }
+
         [Test]
         public function testSetChildIndex():void
         {