带有扩展器样式的弹出窗口动态重定位

Question

我真的在寻找一种好属性，以便在调整窗口大小时使Popup跟随扩展器。

将扩展器和弹出窗口定义为样式，但是如果扩展器随窗口向右移动而不是弹出窗口

如果我们看一下控件模板：

<ControlTemplate x:Key="RightExpander" TargetType="{x:Type Expander}">
        <Border SnapsToDevicePixels="true" Background="{TemplateBinding Background}" 
                            BorderBrush="{TemplateBinding BorderBrush}" 
                            CornerRadius="3">
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="0"/>                      
                </Grid.RowDefinitions>

                <ToggleButton Width="{TemplateBinding ActualWidth}"   Margin="0,1,0,1" MinHeight="0" MinWidth="30" x:Name="HeaderSite" 
                                          Style="{StaticResource LeftPanelCollpasedButtonStyle}" Content="{TemplateBinding Header}" 
                                          ContentTemplate="{TemplateBinding HeaderTemplate}" 
                                          ContentTemplateSelector="{TemplateBinding HeaderTemplateSelector}" 
                                          FontFamily="{TemplateBinding FontFamily}" FontSize="{TemplateBinding FontSize}" 
                                          FontStretch="{TemplateBinding FontStretch}" FontStyle="{TemplateBinding FontStyle}" 
                                          FontWeight="{TemplateBinding FontWeight}" Foreground="{TemplateBinding Foreground}" 
                                          HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" 
                                          Padding="{TemplateBinding Padding}" 
                                          VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" 
                                          IsChecked="{Binding Path=IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" DockPanel.Dock="Top"/>

                <Popup x:Name="popup" AllowsTransparency="False" Margin="0,1,0,1" IsOpen="False" Placement="Bottom"  PlacementTarget="{Binding RelativeSource={RelativeSource TemplatedParent}}">



                    <Grid >


                        <ContentControl x:Name="shadow"  Visibility="Collapsed" HorizontalAlignment="Stretch" Style="{DynamicResource ShadowTemplate}" 
                    VerticalAlignment="Stretch" Content="ContentControl"  Opacity="1" 
                    Margin="2,0,2,0" Foreground="#FF000000"/>
                        <ContentPresenter Opacity="1" MinWidth="220"  HorizontalAlignment="Left" Margin="0,0,0,0" x:Name="ExpandSite" Focusable="false" Visibility="Collapsed" VerticalAlignment="Top" />
                    </Grid>

                </Popup>
            </Grid>
        </Border>
        <ControlTemplate.Triggers>


            <Trigger Property="IsExpanded" Value="true">
                <Setter TargetName="shadow" Property="Visibility" Value="Visible"/>
                <Setter TargetName="popup" Property="Placement" Value="Right"/>
                <Setter TargetName="popup" Property="HorizontalOffset" Value="-5"/>
                <Setter TargetName="popup" Property="IsOpen" Value="true"/>
                <Setter TargetName="ExpandSite" Property="Margin" Value="5,5,5,5"/>


                <Setter Property="Visibility" TargetName="ExpandSite" Value="Visible"/>
            </Trigger>


            <Trigger Property="IsEnabled" Value="false">
                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                <Setter TargetName="shadow" Property="Visibility" Value="Visible"/>
                <Setter TargetName="popup" Property="Placement" Value="Right"/>
                <Setter TargetName="popup" Property="HorizontalOffset" Value="-5"/>
                <Setter TargetName="popup" Property="IsOpen" Value="true"/>
                <Setter TargetName="ExpandSite" Property="Margin" Value="5,5,5,5"/>
                <Setter Property="Visibility" TargetName="ExpandSite" Value="Visible"/>
            </Trigger>




        </ControlTemplate.Triggers>
    </ControlTemplate>

定义了Popup的行指示“ Placement”和“ PlacementTarget”，但是无论我如何更改，它都不会对行为产生影响。 我认为我需要一些触发器，但是我不知道从哪里开始。如果有人可以帮助我，那就太好了。

我以这种方式在代码中使用controltemplate：

<Expander Header="MyExpander" Grid.Row="0" Style="{DynamicResource OutlookStyleExpanderStyle}" IsExpanded="true", Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" x:Name="proc" HorizontalAlignment="Left" Width="350" Margin="0,0,0,0">                                      



                                                    <StackPanel Orientation="Vertical" Grid.Row="0" >
                                                        <StackPanel Orientation="Horizontal">
                                                            <Label FontSize="9" >LabelA</Label>
                                                            <TextBox Width="30"/>
                                                            <Label  FontSize="9" >LabelB</Label>
                                                            <TextBox Width="30"/>
                                                        </StackPanel>                                         

                                                        </Expander>