textbox获取焦点选中内容

前台：

 1     <TextBox VerticalAlignment="Center" HorizontalAlignment="Center" Text="Hover and focus here" Width="150">
 2             <TextBox.Style>
 3                 
 4                 <Style TargetType="TextBox">
 5                     <Style.Triggers>
 6                         <MultiTrigger>
 7                             <MultiTrigger.Conditions>
 8                                 <Condition Property="IsKeyboardFocused" Value="True" />
 9                                 <Condition Property="IsMouseOver" Value="True" />
10                             </MultiTrigger.Conditions>
11                             <MultiTrigger.Setters>
12                                 <Setter Property="Background" Value="LightGreen" />
13                                
14                             </MultiTrigger.Setters>
15                         </MultiTrigger>
16                     </Style.Triggers>
17 
18                     <EventSetter Event="PreviewMouseUp" Handler="TextBox_MouseDown"/>
19                 </Style>
20               
21             </TextBox.Style>
22         </TextBox>

后台：

1    private void TextBox_MouseDown(object sender, MouseButtonEventArgs e)
2         {
3            // MessageBox.Show("ok");
4             TextBox tb = sender as TextBox;
5             tb.SelectAll();
6 
7         }