allow tabbar to response to property changes on buttons

haxe/ui/components/TabBar.hx

@@ -442,6 +442,7 @@ private class Builder extends CompositeBuilder {
 
     }
 
+    private var _childToButtonMap:Map<Component, TabBarButton> = new Map<Component, TabBarButton>();
     private function createTabBarButton(child:Component):TabBarButton {
         var button = new TabBarButton();
 
@@ -471,9 +472,21 @@ private class Builder extends CompositeBuilder {
             button.styleNames = child.styleNames;
         }
 
+        _childToButtonMap.set(child, button);
+        child.registerEvent(UIEvent.PROPERTY_CHANGE, onButtonPropertyChange);
+
         return button;
     }
 
+    private function onButtonPropertyChange(event:UIEvent) {
+        if (event.data == "text") {
+            var button = _childToButtonMap.get(event.target);
+            if (button != null) {
+                button.text = event.target.text;
+            }
+        }
+    }
+
     private override function get_numComponents():Null<Int> {
         return _container.numComponents;
     }