VRCMelonAssistant/ModAssistant/Styles/ComboBox.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style TargetType="ComboBox">
        <Setter Property="Foreground" Value="{DynamicResource TextColor}"/>
        <Setter Property="BorderBrush" Value="{DynamicResource ComboBoxOutline}"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ComboBox}">
                    <Grid Name="templateRoot" SnapsToDevicePixels="True">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*" />
                            <ColumnDefinition MinWidth="{DynamicResource SystemParameters.VerticalScrollBarWidthKey}" Width="0" />
                        </Grid.ColumnDefinitions>
                        <Popup
                            Name="PART_Popup"
                            AllowsTransparency="True"
                            Placement="Bottom"
                            Grid.ColumnSpan="2"
                            PopupAnimation="Slide"
                            IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}">
                            <Border
                                Name="DropDownBorder"
                                BorderBrush="{DynamicResource ComboBoxOutline}"
                                Background="{DynamicResource ComboBoxBackground}"
                                BorderThickness="1"
                                MinWidth="{Binding ActualWidth, ElementName=templateRoot}">
                                <ScrollViewer Name="DropDownScrollViewer">
                                    <Grid Name="grid" RenderOptions.ClearTypeHint="Enabled">
                                        <Canvas
                                            Name="canvas"
                                            HorizontalAlignment="Left"
                                            VerticalAlignment="Top"
                                            Height="0"
                                            Width="0">
                                            <Rectangle
                                                Name="OpaqueRect"
                                                Fill="{Binding Background, ElementName=DropDownBorder}"
                                                MinHeight="{Binding ActualHeight, ElementName=DropDownBorder}"
                                                MinWidth="{Binding ActualWidth, ElementName=DropDownBorder}" />
                                        </Canvas>
                                        <ItemsPresenter
                                            Name="ItemsPresenter"
                                            KeyboardNavigation.DirectionalNavigation="Contained"
                                            SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
                                    </Grid>
                                </ScrollViewer>
                            </Border>
                        </Popup>
                        <Border
                            Name="Border"
                            Background="Transparent"
                            Margin="0">
                            <TextBox
                                Name="PART_EditableTextBox"
                                Margin="2.5"
                                BorderBrush="Transparent"
                                BorderThickness="0"
                                Foreground="{DynamicResource TextColor}"
                                HorizontalContentAlignment="Left"
                                VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
                                IsReadOnly="True"
                                Background="Transparent"
                                Text="{TemplateBinding Text}"/>
                        </Border>
                        <ToggleButton
                            Name="toggleButton"
                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
                            IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" />
                    </Grid>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsEnabled" Value="False">
                            <Setter TargetName="Border" Property="UIElement.Opacity" Value="0.56" />
                        </Trigger>
                        <Trigger Property="UIElement.IsKeyboardFocusWithin" Value="True">
                            <Setter Property="Foreground" Value="#FF000000" />
                        </Trigger>
                        <Trigger SourceName="PART_Popup" Property="Popup.HasDropShadow" Value="True">
                        </Trigger>
                        <Trigger Property="ItemsControl.HasItems" Value="False">
                            <Setter TargetName="DropDownBorder" Property="Height" Value="95" />
                        </Trigger>
                        <MultiTrigger>
                            <MultiTrigger.Conditions>
                                <Condition Property="ItemsControl.IsGrouping" Value="True" />
                                <Condition Property="VirtualizingPanel.IsVirtualizingWhenGrouping" Value="False" />
                            </MultiTrigger.Conditions>
                            <Setter Property="ScrollViewer.CanContentScroll" Value="False" />
                        </MultiTrigger>
                        <Trigger SourceName="DropDownScrollViewer" Property="CanContentScroll" Value="False">
                            <Setter TargetName="OpaqueRect" Property="Canvas.Top" Value="{Binding VerticalOffset, ElementName=DropDownScrollViewer}" />
                            <Setter TargetName="OpaqueRect" Property="Canvas.Left" Value="{Binding HorizontalOffset, ElementName=DropDownScrollViewer}" />
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Style.Triggers>
            <Trigger Property="ComboBox.IsEditable" Value="True">
                <Setter Property="IsTabStop" Value="False" />
                <Setter Property="Padding" Value="2" />
            </Trigger>
        </Style.Triggers>
    </Style>
</ResourceDictionary>