WPF气泡提示框的简单制作

<TextBox Name="account" GotFocus="account_GotFocus" LostFocus="account_LostFocus" Style="{StaticResource LabelTextBox}" xl:ControlAttachProperty.Label="用户名:" Foreground="Black" Margin="10,10,273,271" Width="Auto" />

<Popup Name="pop3" AllowsTransparency="True" StaysOpen="True" PopupAnimation="Fade" IsOpen="False" PlacementTarget="{Binding ElementName=account}" Placement="Right" >  <Label Style="{StaticResource tipLable}">    <StackPanel Orientation="Horizontal">     <Label Content="请输入用户名"/>    </StackPanel>  </Label> </Popup>

<Style TargetType="Label" x:Key="tipLable">  <Setter Property="Template">   <Setter.Value>    <ControlTemplate TargetType="{x:Type Label}">     <Grid>      <Border CornerRadius="4" BorderBrush="Black" BorderThickness="1" VerticalAlignment="Top" Margin="8.5,0,0,0" Background="Yellow" HorizontalAlignment="Left" Padding="5">       <ContentPresenter />      </Border>      <Canvas Width="10" Height="10" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="0,10,0,0" Background="Transparent">       <Path Stroke="Black" StrokeThickness="0.5" Fill="Yellow">        <Path.Data>         <PathGeometry Figures="M 10,0 L 10,0,0,5 L 0,5,10,10"/>        </Path.Data>       </Path>      </Canvas>     </Grid>    </ControlTemplate>   </Setter.Value>  </Setter> </Style>