vb.net - Windows 10 Universal App compiled Bindings / x:bind not working -

i've got following code test out new compiled bindings in universal windows 10 apps.

xaml:

<page x:class="xbindtest.mainpage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:xbindtest" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:ignorable="d" datacontext="{binding relativesource={relativesource self}}">  <grid background="{themeresource applicationpagebackgroundthemebrush}">     <stackpanel horizontalalignment="center" verticalalignment="center">          <textblock x:name="tester" text="{x:bind mybindclass.testtext, mode=oneway}" ></textblock>         <textblock x:name="tester2" text="{binding mybindclass.testtext, mode=oneway}" ></textblock>         <button x:name="button" content="button" horizontalalignment="stretch" verticalalignment="stretch"/>      </stackpanel>              </grid> 

code behind:

public class xbindclass : implements inotifypropertychanged      private _testtext string      public property testtext string                     return _testtext         end         set(value string)              if _testtext <> value                  _testtext = value                 notifypropertychanged("testtext")              end if         end set     end property      public event propertychanged propertychangedeventhandler implements inotifypropertychanged.propertychanged      private sub notifypropertychanged(<callermembername> optional propertyname string = "")         raiseevent propertychanged(me, new propertychangedeventargs(propertyname))     end sub  end class  ''' <summary> ''' empty page can used on own or navigated within frame. ''' </summary> public notinheritable class mainpage     inherits page       public property mybindclass xbindclass      public sub new()          ' add initialization after initializecomponent() call.          mybindclass = new xbindclass {.testtext = "hello"}          ' call required designer.         initializecomponent()      end sub      private sub button_click(sender object, e routedeventargs) handles button.click         mybindclass.testtext &= " there"          tester.datacontext = mybindclass.testtext      end sub end class 

i'm testing 2 binding types side side... standard {binding...} type working fine, new x:bind isn't working strangely...

perhaps i'm misunderstanding how new binding works? understood, x:bind bound codebehind, , required public property bind to, , off , running.

i'm using vs2015 rc , win 10 build 10130.

turns out x:bind isn't implemented in vb.net vs2015rc.ms have confirmed implemented in full rtm