将文本数据绑定到字符串属性

我是Silverlight和数据绑定概念的新手，但我仍然无法解决问题。经过几天的研究，我还没找到解决方案。

这是我的问题：

我正确地将String属性绑定到我的TextBlock的文本，如下所示：

主页.xaml

<Grid  Background="Blue"  DataContext="{StaticResource WP8Displayable}">
        <TextBlock x:Name="tbCanvasTitle" TextWrapping="Wrap" Text="{Binding titleDisplayable}" FontWeight="Bold" HorizontalAlignment="Center"/>          
</Grid>

WP8可显示.cs

public class WP8Displayable : IDisplayable, INotifyPropertyChanged
{
    public String title { get; set; }

    #region INotifyPropertyChanged Members

    public string titleDisplayable
    {
        get
        {
            return title;
        }
        set
        {
            if (title != value)
            {
                title = value;
                NotifyPropertyChanged("titleDisplayable");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    // Used to notify the page that a data context property changed
    private void NotifyPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
    #endregion
    public void setTitle(String s)
    {
        this.title = s;
        NotifyPropertyChanged("titleDisplayable");
    }
}

我的MainPage.xaml.cs中有一个线程，它可以实例化WP8Displayable类的一个或多个实例。当其中一个实例调用setTitle(String s)时，我的TextBlock中的文本没有更新，似乎我的DataContext设置不正确。

编辑：

我的线程在MainPage_Loaded(object sender, RoutedEventArgs e)方法中的MainPage.xaml.cs中启动，并执行如下操作：

  var instanceWP8Displayable = new WP8Displayable();
  //tbCanvasTitle.DataContext = instanceWP8Displayable;   HERE IS WHAT I WOULD LIKE TO DO ON XAML
  instanceWP8Displayable.setTitle("my Title");

编辑2:App.xaml

<Application
x:Class="AMS.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:windows="clr-namespace:System.Windows;assembly=System.Windows"
xmlns:ioC="clr-namespace:AMS.Controller">
<!--Application Resources-->
<Application.Resources>
    <windows:ResourceDictionary>
        <local:LocalizedStrings xmlns:local="clr-namespace:AMS" x:Key="LocalizedStrings"/>
        <ioC:Locator x:Key="Locator" x:Name="Locator" />
    </windows:ResourceDictionary>
</Application.Resources>

主页.xaml

    <Grid x:Name="LayoutRoot" Background="White">
        <Grid  Background="Blue"  DataContext="{Binding Source={StaticResource Locator}, Path=WP8Displayable}">
        <TextBlock x:Name="tbCanvasTitle" TextWrapping="Wrap" Text="{Binding titleDisplayable}" FontWeight="Bold" HorizontalAlignment="Center"/>          
    </Grid>
    <Grid.DataContext>
        <local:WP8Displayable />
    </Grid.DataContext>
    </Grid>

在这种情况下，我如何动态设置DataContext？是否可以将多个实例链接到同一对象

如果有人作为线索或觉得我的问题不够清楚，请毫不犹豫地告诉我。

谢谢。

public class Locator
{
    public WP8Displayable WP8Displayable
    {
        get { return new WP8Displayable(); }
    }
}

<Application
    ...
    xmlns:windows="clr-namespace:System.Windows;assembly=System.Windows"
    xmlns:ioC="clr-namespace:YOURAPPNAME">
 <!--Application Resources-->
 <Application.Resources>      
     <windows:ResourceDictionary>
         <local:LocalizedStrings xmlns:local="clr-namespace:AMS" x:Key="LocalizedStrings"/>
         <ioC:Locator x:Key="Locator" x:Name="Locator" />
     </windows:ResourceDictionary>
 </Application.Resources>

        ...
</Application>

<Grid  Background="Blue"  DataContext="{Binding Source={StaticResource Locator}, Path=WP8Displayable}">
        <TextBlock x:Name="tbCanvasTitle" TextWrapping="Wrap" Text="{Binding titleDisplayable}" FontWeight="Bold" HorizontalAlignment="Center"/>          
</Grid>

#region INotifyPropertyChanged Members
public string _titleDisplayable;
public string titleDisplayable
{
    get
    {
        return _titleDisplayable;
    }
    set
    {
        if (_titleDisplayable != value)
        {
            _titleDisplayable = value;
            NotifyPropertyChanged("titleDisplayable");
        }
    }
}

public void setTitle(string s)
{
    this.titleDisplayable = s;
}