wpf - combobox style css

Personalizar el ScrollViewer en WPF

Question

Estoy desarrollando una aplicación que tiene el ComboBox personalizado.

La apariencia de ComboBox debería gustarle.

He modificado el ControlTemplate de ComboBox para que se vea como el anterior.

El problema es: cuando Up RepeatButton está desactivado también (programáticamente estoy desactivando eso) los elementos se seleccionan cuando sigo presionando el botón Repeat desactivado.

La plantilla de control que estoy usando es:

            <Setter
                Property    ="SnapsToDevicePixels"
                Value       ="True"
                />

            <Setter
                Property    ="FocusVisualStyle"
                Value       ="{DynamicResource ComboFocusVisualStyle}"
                />

            <Setter
                Property    ="Foreground"
                Value       ="Black"
                />

            <Setter
                Property    ="Template"
                >

                <Setter.Value>

                    <ControlTemplate
                        TargetType  ="{x:Type ComboBox}"
                        >

                        <Grid>

                            <Border 
                                CornerRadius    ="3"
                                BorderThickness ="0,0,0,.7" 
                                BorderBrush     ="WhiteSmoke"
                                >

                                <Border 
                                    Name                ="brd1"
                                    CornerRadius        ="3"                                          
                                    BorderBrush         ="{StaticResource ComboBorderBrush}" 
                                    BorderThickness     ="1,1,1,1"
                                    Background          ="{TemplateBinding Background}"                                       
                                    ToolTip             ="{TemplateBinding SelectionBoxItem, Converter={StaticResource ToolTipConverter}, ConverterParameter=PrinterInfoCol}"
                                    >

                                    <Grid>

                                        <ContentPresenter
                                            x:Name              ="ContentSite"
                                            HorizontalAlignment ="Left" 
                                            VerticalAlignment   ="Center"
                                            IsHitTestVisible    ="False"
                                            >

                                            <ContentPresenter.Content>

                                                <Grid
                                                    Width    ="180"
                                                    >

                                                    <Grid.ColumnDefinitions>

                                                        <ColumnDefinition
                                                            Width   ="180"
                                                            />

                                                    </Grid.ColumnDefinitions>

                                                        <TextBlock
                                                            Grid.Column         ="0"
                                                            Margin              ="10,0,0,0"
                                                            Text                ="{TemplateBinding SelectionBoxItem, Converter={StaticResource TextConverter}}"
                                                            TextTrimming        ="CharacterEllipsis"
                                                            VerticalAlignment   ="Center"
                                                            Foreground          ="Black"                                                                
                                                            />

                                                    </Grid>

                                            </ContentPresenter.Content>

                                        </ContentPresenter>

                                        <!-- The ToggleButton is databound to the ComboBox itself to toggle IsDropDownOpen -->
                                        <ToggleButton 
                                            x:Name          ="ToggleButton" 
                                            Template        ="{DynamicResource ComboBoxToggleButton}" 
                                            Focusable       ="false" 
                                            IsChecked       ="{Binding Path=IsDropDownOpen, 
                                                                       Mode =TwoWay, 
                                                                       RelativeSource  ={RelativeSource TemplatedParent}}" 
                                            ClickMode       ="Press"
                                            Margin          ="16,5,2,2"                                           
                                            />

                                    </Grid>

                                </Border>

                            </Border>

                            <!-- The Popup shows the list of items in the 
                            ComboBox. IsOpen is databound to IsDropDownOpen 
                            which is toggled via the ComboBoxToggleButton -->
                            <Popup 
                                x:Name                                      ="PART_popup" 
                                IsOpen                                      ="{TemplateBinding IsDropDownOpen}" 
                                ScrollViewer.VerticalScrollBarVisibility    ="Auto"
                                Placement                                   ="Bottom" 
                                Focusable                                   ="False" 
                                MinWidth                                    ="{Binding ElementName=brd1, Path=ActualWidth}"
                                AllowsTransparency                          ="True" 
                                PopupAnimation                              ="None"                                  
                                MaxWidth                                    ="325"
                                >

                                <dropShadow:SystemDropShadowChrome 
                                    Visibility      ="Visible" 
                                    Margin          ="3"                                           
                                    >

                                    <Grid                                                    
                                        x:Name              ="DropDown"                                            
                                        SnapsToDevicePixels ="True"
                                        Margin               ="0,-1,0,0"  
                                        >

                                        <Grid.RowDefinitions>
                                            <RowDefinition
                                                Height="18"
                                                />
                                            <RowDefinition
                                                Height="*"
                                                />
                                            <RowDefinition
                                                Height="18"
                                                />
                                        </Grid.RowDefinitions>


                                        <Border 
                                            x:Name          ="DropDownBorder"
                                            Grid.Row="0"
                                            Grid.RowSpan="3"
                                            Background      ="{StaticResource dropDownBackground}"                                              
                                            BorderBrush     ="{DynamicResource SolidBorderBrush}" 
                                            BorderThickness ="1"
                                            />

                                        <RepeatButton
                                            x:Name      ="upRepeatButton"
                                            Grid.Row    ="0"
                                            Margin      ="1,0"
                                            ClickMode   ="Press"
                                            Style       ="{DynamicResource ScrollBarLineButton}"
                                            Height      ="18"                       
                                            Content     ="M 0 4 L 8 4 L 4 0 Z"
                                            />

                                        <ScrollViewer 
                                            Name                            ="scrollCombo"
                                            Margin                          ="1,0,1,0"
                                            Style                           ="{DynamicResource ComboBoxScrollViewerStyle}"                                          
                                            Grid.Row                        ="1"
                                            SnapsToDevicePixels             ="True" 
                                            HorizontalScrollBarVisibility   ="Hidden" 
                                            VerticalScrollBarVisibility     ="Hidden" 
                                            CanContentScroll                ="False"
                                            HorizontalAlignment             ="Stretch"
                                            Focusable                       ="False"
                                            >

                                            <ItemsPresenter
                                                Margin="0,18"
                                                />


                                        </ScrollViewer>

                                        <RepeatButton
                                            x:Name      ="downRepeatButton"
                                            Grid.Row    ="2"
                                            Margin      ="1,0"
                                            ClickMode   ="Press"
                                            Style       ="{StaticResource ScrollBarLineButton}"
                                            Height      ="18"                        
                                            Content     ="M 0 0 L 4 4 L 8 0 Z"
                                            />

                                    </Grid>

                                </dropShadow:SystemDropShadowChrome>

                            </Popup>

                        </Grid>

                        <ControlTemplate.Triggers>

                            <!-- This forces the DropDown to have a minimum
                            size if it is empty -->
                            <Trigger
                                Property    ="HasItems"
                                Value       ="false"
                                >

                                <Setter
                                    Property    ="MinHeight"
                                    Value       ="95"
                                    TargetName  ="DropDownBorder"
                                    />

                            </Trigger>

                            <Trigger
                                Property    ="IsGrouping"
                                Value       ="True"
                                >

                                <Setter
                                    Property    ="ScrollViewer.CanContentScroll"
                                    Value       ="false"
                                    />

                            </Trigger>

                        </ControlTemplate.Triggers>

                    </ControlTemplate>

                </Setter.Value>

            </Setter>

        </Style>        

Alguna idea sobre esto?