WPF自定义ComboBox实现文本区域可点击的技术问询

我在WPF应用中使用了一个自定义样式的ComboBox，目前仅箭头区域可触发下拉展开，需求是让文本显示区域也能点击展开下拉框。接触WPF开发已有数月，但对UI组件定制仍存在困难，ComboBox的定制尤其棘手。尝试过相关解决方案，但UI渲染效果异常，恳请提供技术指导。

当前效果与异常效果 #

页面Xaml代码 #

<Border Height="35"
        VerticalAlignment="Top"
        Background="#fafafa"
        CornerRadius="2">
    <ComboBox Width="Auto"
              Height="30"
              VerticalAlignment="Center"
              ItemsSource="{Binding NetGrossItemSource}"
              SelectedItem="{Binding SelectedProductionType}"
              Style="{StaticResource CustomComboBox}">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock VerticalAlignment="Center"
                           FontSize="14"
                           Foreground="{StaticResource font-gray}"
                           Text="{Binding}" />
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>
</Border>

ComboBox自定义样式代码 #

<Style x:Key="CustomComboBox" TargetType="{x:Type ComboBox}">
    <Setter Property="SnapsToDevicePixels" Value="true" />
    <Setter Property="OverridesDefaultStyle" Value="true" />
    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto" />
    <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
    <Setter Property="ScrollViewer.CanContentScroll" Value="true" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ComboBox}">
                <Grid>
                    <ToggleButton
                        x:Name="ToggleButton"
                        Grid.Column="2"
                        Margin="0,-2,0,0"
                        HorizontalAlignment="Right"
                        ClickMode="Press"
                        Focusable="false"
                        IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
                        Template="{StaticResource ComboBoxToggleButton}" />
                    <ContentPresenter
                        x:Name="ContentSite"
                        Margin="3,3,23,3"
                        HorizontalAlignment="Left"
                        VerticalAlignment="Stretch"
                        Content="{TemplateBinding SelectionBoxItem}"
                        ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
                        ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
                        IsHitTestVisible="False"
                        TextBlock.FontWeight="Medium" />
                    <Popup
                        x:Name="Popup"
                        AllowsTransparency="True"
                        Focusable="False"
                        IsOpen="{TemplateBinding IsDropDownOpen}"
                        Placement="Bottom"
                        PopupAnimation="Slide">
                        <Grid
                            x:Name="DropDown"
                            MinWidth="{TemplateBinding ActualWidth}"
                            MaxHeight="{TemplateBinding MaxDropDownHeight}"
                            SnapsToDevicePixels="True">
                            <Border
                                x:Name="DropDownBorder"
                                BorderThickness="1"
                                CornerRadius="4">
                                <Border.BorderBrush>
                                    <SolidColorBrush Color="#ADB7C9" />
                                </Border.BorderBrush>
                                <Border.Background>
                                    <SolidColorBrush Color="White" />
                                </Border.Background>

                            </Border>
                            <ScrollViewer
                                Margin="0"
                                Padding="2,4"
                                SnapsToDevicePixels="True">
                                <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
                            </ScrollViewer>
                        </Grid>
                    </Popup>
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="Normal" />
                            <VisualState x:Name="MouseOver" />
                            <VisualState x:Name="Disabled">
                                <Storyboard>
                                    <ColorAnimationUsingKeyFrames Storyboard.TargetName="PART_EditableTextBox" Storyboard.TargetProperty="(TextElement.Foreground).(SolidColorBrush.Color)">
                                        <EasingColorKeyFrame KeyTime="0" Value="#FF888888" />
                                    </ColorAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                        <VisualStateGroup x:Name="EditStates">
                            <VisualState x:Name="Editable">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="PART_EditableTextBox" Storyboard.TargetProperty="(UIElement.Visibility)">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Visible}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentSite" Storyboard.TargetProperty="(UIElement.Visibility)">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Uneditable" />
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="HasItems" Value="false" />
                    <Trigger Property="IsGrouping" Value="true">
                        <Setter Property="ScrollViewer.CanContentScroll" Value="false" />
                    </Trigger>
                    <Trigger SourceName="Popup" Property="AllowsTransparency" Value="true">
                        <Setter TargetName="DropDownBorder" Property="CornerRadius" Value="4" />
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

尝试过相关解决方案，但UI渲染效果不符合预期。

内容的提问来源于stack exchange，提问作者May Nguyen