<ScrollViewer  x:Name="scrollViewer" Margin="0,10"    Grid.Row="0" HorizontalScrollBarVisibility="Disabled" VerticalScrollBarVisibility="Auto"  >
                    <ItemsControl Name="items" ItemsSource="{Binding PreferenceGroups}">
                    <ItemsControl.Resources>
                        <ItemsPanelTemplate x:Key="wrapPanel">
                            <WrapPanel></WrapPanel>
                        </ItemsPanelTemplate>

                        <DataTemplate x:Key="SoloSelection">
                            <ItemsControl ItemsSource="{Binding .}" ItemsPanel="{StaticResource wrapPanel}">
                                <ItemsControl.DataContext>
                                    <MultiBinding Converter="{StaticResource prefConv}">
                                        <Binding Path="."></Binding>
                                        <Binding ElementName="viewModel" Path="DataContext.OrderItem.Preferences"></Binding>
                                    </MultiBinding>
                                </ItemsControl.DataContext>
                                <ItemsControl.ItemTemplate>
                                    <DataTemplate>
                                        <local:RadioButtonToggle
                                             Width="146" Height="58" Margin="0,0,4,4" GroupName="{Binding Path=Preference.GroupId}" Style="{StaticResource OrderRadioButton}" >
                                         <i:Interaction.Triggers>
                                                <i:EventTrigger EventName="Unchecked">
                                                    <cal:ActionMessage MethodName="RemovePreference">
                                                        <cal:Parameter Value="$dataContext" />
                                                           <cal:Parameter Value="false" />
                                                    </cal:ActionMessage>
                                                </i:EventTrigger>
                                                <i:EventTrigger EventName="Checked">
                                                    <cal:ActionMessage MethodName="AddPreference">
                                                        <cal:Parameter Value="$dataContext" />
                                                           <cal:Parameter Value="false" />
                                                    </cal:ActionMessage>
                                                </i:EventTrigger>
                                            </i:Interaction.Triggers>



                                            <TextBlock   Margin="4,0,3,0" VerticalAlignment="Center" TextWrapping="Wrap" Text="{Binding Preference.Name}"></TextBlock>

                                            <local:RadioButtonToggle.IsChecked>
                                                <MultiBinding Mode="OneTime" Converter="{StaticResource prefCheckedConv}">
                                                    <Binding Path="."></Binding>
                                                    <Binding ElementName="viewModel" Path="DataContext.OrderItem.Preferences"></Binding>
                                                </MultiBinding>
                                            </local:RadioButtonToggle.IsChecked>
                                        </local:RadioButtonToggle>
                                    </DataTemplate>
                                </ItemsControl.ItemTemplate>
                            </ItemsControl>
                        </DataTemplate>

                        <DataTemplate x:Key="MultiSelection">
                            <ItemsControl ItemsSource="{Binding .}"  ItemsPanel="{StaticResource wrapPanel}">
                                <ItemsControl.DataContext>
                                    <MultiBinding  Converter="{StaticResource prefConv}">
                                        <Binding Path="."></Binding>
                                        <Binding ElementName="viewModel" Path="DataContext.OrderItem.Preferences"></Binding>
                                    </MultiBinding>
                                </ItemsControl.DataContext>
                                <ItemsControl.ItemTemplate>
                                    <DataTemplate>
                                        <CheckBox
                                            cal:Message.Attach="[Event Checked]=[Action AddPreference($dataContext,false)]; [Event Unchecked]=[Action RemovePreference($datacontext,false)]"
                                            Width="146" Height="58" Margin="0,0,4,4"   Style="{StaticResource OrderCheckboxButton}">
                                            <TextBlock  Margin="4,0,3,0" VerticalAlignment="Center" TextWrapping="Wrap" Text="{Binding Preference.Name}"></TextBlock>
                                            <CheckBox.IsChecked>
                                                <MultiBinding Mode="OneTime" Converter="{StaticResource prefCheckedConv}">
                                                    <Binding Path="."></Binding>
                                                    <Binding ElementName="viewModel" Path="DataContext.OrderItem.Preferences"></Binding>
                                                </MultiBinding>
                                            </CheckBox.IsChecked>

                                        </CheckBox>
                                    </DataTemplate>
                                </ItemsControl.ItemTemplate>
                            </ItemsControl>
                        </DataTemplate>

                        <DataTemplate x:Key="MultiQuantitySelection">
                            <ItemsControl ItemsSource="{Binding .}" ItemsPanel="{StaticResource wrapPanel}">
                                <ItemsControl.DataContext>
                                    <MultiBinding Converter="{StaticResource prefConv}">
                                        <Binding Path="."></Binding>
                                        <Binding ElementName="viewModel" Path="DataContext.OrderItem.Preferences"></Binding>
                                    </MultiBinding>
                                </ItemsControl.DataContext>

                                <ItemsControl.ItemTemplate>
                                    <DataTemplate>
                                        <Grid Width="146" Height="58" Margin="0,0,4,4" >
                                            <Grid.ColumnDefinitions>
                                                <ColumnDefinition Width="Auto"></ColumnDefinition>
                                                <ColumnDefinition Width="*"></ColumnDefinition>
                                            </Grid.ColumnDefinitions>
                                            <Button Name="quantity"
                                                    Background="#1f1f1f"
                                                    cal:Message.Attach="[Event Click]=[Action RemovePreference($dataContext,'True')]"
                                                  Width="45" Style="{StaticResource OrderProductButton}" >
                                                <TextBlock Text="{Binding Quantity}"></TextBlock>
                                            </Button>
                                            <Button
                                                   cal:Message.Attach="[Event Click]=[Action AddPreference($dataContext,'True')]"
                                                   Margin="-1,0,0,0" Grid.Column="1" HorizontalAlignment="Stretch"  HorizontalContentAlignment="Left" Style="{StaticResource OrderProductButton}">
                                                <TextBlock  TextWrapping="Wrap" HorizontalAlignment="Left"  TextTrimming="CharacterEllipsis"  Text="{Binding Path=Preference.Name}" ></TextBlock>

                                            </Button>
                                        </Grid>
                                        <DataTemplate.Triggers>
                                            <DataTrigger   Binding="{common:ComparisonBinding DataContext.Quantity,GT,0}" Value="{x:Null}">
                                                <DataTrigger.Setters>
                                                    <Setter Value="{StaticResource BackgroundSelected}" Property="Background" TargetName="quantity"/>
                                                </DataTrigger.Setters>
                                            </DataTrigger>
                                        </DataTemplate.Triggers>

                                    </DataTemplate>
                                </ItemsControl.ItemTemplate>


                            </ItemsControl>
                        </DataTemplate>
                    </ItemsControl.Resources>

                    <ItemsControl.ItemTemplate>
                        <DataTemplate>
                            <StackPanel>
                                <TextBlock FontSize="25"  FontWeight="Light"  Margin="0,8,0,5" Text="{Binding Name}"></TextBlock>
                                <!-- Εδω τα items -->
                                <ContentControl  Content="{Binding Preferences}" Name="items"></ContentControl>
                            </StackPanel>

                            <DataTemplate.Triggers>
                                <DataTrigger Binding="{Binding Path=SelectionMode}" Value="1">
                                    <Setter TargetName="items" Property="ContentTemplate" Value="{StaticResource SoloSelection}"/>
                                </DataTrigger>

                                <DataTrigger Binding="{Binding Path=SelectionMode}" Value="2">
                                    <Setter TargetName="items" Property="ContentTemplate" Value="{StaticResource MultiSelection}"/>
                                </DataTrigger>
                                <DataTrigger Binding="{Binding Path=SelectionMode}" Value="3">
                                    <Setter TargetName="items" Property="ContentTemplate" Value="{StaticResource MultiQuantitySelection}"/>
                                </DataTrigger>
                            </DataTemplate.Triggers>

                        </DataTemplate>
                    </ItemsControl.ItemTemplate>
                    <ItemsControl.ItemsPanel>
                        <ItemsPanelTemplate>
                                <StackPanel  Orientation="Vertical"></StackPanel >
                        </ItemsPanelTemplate>
                    </ItemsControl.ItemsPanel>



                </ItemsControl>
                  </ScrollViewer>