Tukukkk

I am really looking for the good property to get the Popup follow the expander when the window is resized.

The expander and the popup are define into a Style, but if the Expander moves right with the window but not the popup

If we look at the controltemplate:

<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>

The line where the Popup is defined indicate "Placement" and "PlacementTarget" but it doesnt have an impact on the behaviour, whatever I changed.
I think I need some triggers, but I don't know where to begin with. If someone could help me it would be very nice.

I use the controltemplate in my code in this way :

<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>