WPF中TextBox控件对于鼠标单击获取焦点后的全选

void OnLostFocus(object sender, RoutedEventArgs e)
        {
            TextBox tb = e.Source as TextBox;
            tb.PreviewMouseDown += new MouseButtonEventHandler(OnPreviewMouseDown);
        }

        void OnPreviewMouseDown(object sender, MouseButtonEventArgs e)
        {
            TextBox tb = e.Source as TextBox;
            tb.Focus();
            e.Handled = true;
        }

        void OnGotFocus(object sender, RoutedEventArgs e)
        {
            TextBox tb = e.Source as TextBox;
            tb.SelectAll();
            tb.PreviewMouseDown -= new MouseButtonEventHandler(OnPreviewMouseDown);
        }

<TextBox Name="searchTextBox" Background="DarkOrange" HorizontalAlignment="Stretch" MaxLength="15" TextAlignment ="Center" 
     TextChanged="OnSearchTextChange" GotFocus="OnGotFocus" PreviewMouseDown="OnPreviewMouseDown" LostFocus="OnLostFocus">
     输入名称搜索
</TextBox>

　　关键点在于鼠标按下之时

tb.Focus();
e.Handled = true;

由这里引发GotFocus事件 并且设置Handled 标记阻止路由事件继续传播

在GotFocus的事件里面利用tb.SelectAll()全选

tb.PreviewMouseDown -= new MouseButtonEventHandler(OnPreviewMouseDown);

所实现的功能是当第二次单击的时候，不再是全选文字，而是显示光标。

第一次发博文，欢迎指正。