Update DataGrid.cs

Make sure the update is on UI thread.
Create Window510.xaml
Create Window510.xaml.cs
Update MainWindow.xaml
Update Window510.xaml.cs
Update DataGridDemo_NET45.csproj
Update DataGrid.Content.cs

From RAY:
Fix : Table view display nothing when switching between different table views.

The text block controls are loaded after the call to this method.
Dispathcher.Invoke doesn't work, because, the dispatcher may be suspended.
Update DataGrid.cs
Merge pull request #24 from ZHZG/master

Make sure the update of datagrid is on UI thread.