Silverlight 4-Datagrid排序和选择已更改问题

我使用的是Silverlight 4，有一个datagrid，允许用户对行进行排序。在sort column事件中，将触发SelectionChanged事件，并选择datagrid中的初始第一行。是否仍有不触发SelectionChanged事件的情况，或者是否有onSort事件将selectedItem设置为null的情况？

这似乎是一个无法通过向SelectionChanged事件添加逻辑轻松解决的问题。我正在做的是从该事件中删除所有代码，并将其放入每行的MouseLeftUpButton事件中。这是它的代码

   Private Sub dgrd_LoadingRow(ByVal sender As Object, ByVal e As System.Windows.Controls.DataGridRowEventArgs)    
      AddHandler e.Row.MouseLeftButtonUp, AddressOf ClientGrid_SelectRow
   End Sub

   Private Sub ClientGrid_SelectRow(ByVal sender As Object, ByVal e As MouseEventArgs)
      Dim SelectedRow As DataGridRow = CType(sender, DataGridRow)

      //SelectedRow.DataContext is equivlent to e.AddedItems(0) in the SelectionChanged Event

      //Add the SelectionChanged logic here 

   End Sub

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添加行处理程序对我不起作用。。。但这确实：

private bool _binding = false;
private void data_grid_LoadingRow(object sender, DataGridRowEventArgs e)
    {
        _binding = true;
    }
 private void data_grid_SelectionChanged(object sender, SelectionChangedEventArgs e)
   {
       if (_binding)
       {
           data_grid.SelectedItem = null;
           _binding = false;
       }
       if (data_grid.SelectedItem==null) return;
       // do something with selected item
   }