Styling the indeterminate state of a WPF checkbox

Question

I want to style the indeterminate state of a WPF checkbox. We have a treeview control with checkboxes, and we want the indeterminate state to represent that some descendants are checked and some are unchecked.

The solution I'm seeing everywhere is to override the default control template for a checkbox and do what I need to do.

I have two problems with that:

1. I can't find the control template for a normal Aero checkbox. This one: http://msdn.microsoft.com/en-us/library/ms752319.aspx looks goofy.

2. The control template I get from Expression Blend has that BulletChrome element in it, and I can't figure out what to do with that.

So does anyone know where to get a checkbox control template that looks "normal" or is there an easier way to just style the indeterminate state by itself?

I'm sure there's an easy way I'm just overlooking... Right?

Answer 1

You can use CheckBox styling from the classic theme located at:

• C:\Program Files (x86)\Microsoft Expression\Blend 4\SystemThemes\Wpf\classic.xaml

This implementation has a Path representing the checkbox mark called CheckMarkPath. I simply replaced this Path with a filled Rectangle to get these results:

Answer 2

The below code is a sample check box with three state.

<Window x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<Window.Resources>
    <!-- Focus Style -->

    <SolidColorBrush x:Key="InputBackgroundFocused" Color="Orange"></SolidColorBrush>

    <Style x:Key="CheckBoxFocusVisualStyle">
        <Setter Property="Control.Template">
            <Setter.Value>
                <ControlTemplate>
                    <Border CornerRadius="2" Margin="0,0,4,3" BorderThickness="2" BorderBrush="{StaticResource InputBackgroundFocused}" Background="Transparent"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <!-- Fill Brushes -->

    <LinearGradientBrush x:Key="NormalBrush" StartPoint="0,0" EndPoint="0,1">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#FFF" Offset="0.0"/>
                <GradientStop Color="#CCC" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <LinearGradientBrush x:Key="HorizontalNormalBrush" StartPoint="0,0" EndPoint="1,0">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#FFF" Offset="0.0"/>
                <GradientStop Color="#CCC" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <LinearGradientBrush x:Key="LightBrush" StartPoint="0,0" EndPoint="0,1">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#FFF" Offset="0.0"/>
                <GradientStop Color="#EEE" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <LinearGradientBrush x:Key="HorizontalLightBrush" StartPoint="0,0" EndPoint="1,0">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#FFF" Offset="0.0"/>
                <GradientStop Color="#EEE" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <LinearGradientBrush x:Key="DarkBrush" StartPoint="0,0" EndPoint="0,1">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#FFF" Offset="0.0"/>
                <GradientStop Color="#AAA" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <LinearGradientBrush x:Key="PressedBrush" StartPoint="0,0" EndPoint="0,1">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#BBB" Offset="0.0"/>
                <GradientStop Color="#EEE" Offset="0.1"/>
                <GradientStop Color="#EEE" Offset="0.9"/>
                <GradientStop Color="#FFF" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <SolidColorBrush x:Key="DisabledForegroundBrush" Color="#888" />

    <SolidColorBrush x:Key="DisabledBackgroundBrush" Color="#EEE" />

    <SolidColorBrush x:Key="WindowBackgroundBrush" Color="#FFF" />

    <SolidColorBrush x:Key="SelectedBackgroundBrush" Color="#DDD" />

    <!-- Border Brushes -->

    <LinearGradientBrush x:Key="NormalBorderBrush" StartPoint="0,0" EndPoint="0,1">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#CCC" Offset="0.0"/>
                <GradientStop Color="#444" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <LinearGradientBrush x:Key="HorizontalNormalBorderBrush" StartPoint="0,0" EndPoint="1,0">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#CCC" Offset="0.0"/>
                <GradientStop Color="#444" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <LinearGradientBrush x:Key="DefaultedBorderBrush" StartPoint="0,0" EndPoint="0,1">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#777" Offset="0.0"/>
                <GradientStop Color="#000" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <LinearGradientBrush x:Key="PressedBorderBrush" StartPoint="0,0" EndPoint="0,1">
        <GradientBrush.GradientStops>
            <GradientStopCollection>
                <GradientStop Color="#444" Offset="0.0"/>
                <GradientStop Color="#888" Offset="1.0"/>
            </GradientStopCollection>
        </GradientBrush.GradientStops>
    </LinearGradientBrush>

    <SolidColorBrush x:Key="DisabledBorderBrush" Color="#AAA" />

    <SolidColorBrush x:Key="SolidBorderBrush" Color="#888" />

    <SolidColorBrush x:Key="LightBorderBrush" Color="#AAA" />

    <!-- Miscellaneous Brushes -->
    <SolidColorBrush x:Key="GlyphBrush" Color="#444" />

    <SolidColorBrush x:Key="LightColorBrush" Color="#DDD" />
    <Style TargetType="{x:Type CheckBox}">
        <Setter Property="SnapsToDevicePixels" Value="true"/>
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="FocusVisualStyle" Value="{DynamicResource CheckBoxFocusVisualStyle}" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="CheckBox">
                    <BulletDecorator Background="Transparent">
                        <BulletDecorator.Bullet>
                            <Border x:Name="Border"  
                              Width="17" 
                              Height="17" 
                              CornerRadius="2" 
                              Background="{StaticResource NormalBrush}"
                              BorderThickness="1"
                              BorderBrush="{StaticResource NormalBorderBrush}">
                                <Path 
                                Width="11" Height="11" 
                                x:Name="CheckMark"
                                SnapsToDevicePixels="False" 
                                Stroke="{StaticResource GlyphBrush}"
                                StrokeThickness="2"
                                Data="M 2,4 C 2,4 3,5 5,13 C 5,13 5,3 12,0" />
                            </Border>
                        </BulletDecorator.Bullet>
                        <ContentPresenter Margin="4,0,0,0"
                            VerticalAlignment="Center"
                            HorizontalAlignment="Left"
                            RecognizesAccessKey="True"/>
                    </BulletDecorator>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsChecked" Value="false">
                            <Setter TargetName="CheckMark" Property="Visibility" Value="Collapsed"/>
                        </Trigger>
                        <Trigger Property="IsChecked" Value="{x:Null}">
                            <Setter TargetName="CheckMark" Property="Data" Value="M 0 7 L 7 0" />
                        </Trigger>
                        <Trigger Property="IsMouseOver" Value="true">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource DarkBrush}" />
                        </Trigger>
                        <Trigger Property="IsPressed" Value="true">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource PressedBrush}" />
                            <Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource PressedBorderBrush}" />
                        </Trigger>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}" />
                            <Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource DisabledBorderBrush}" />
                            <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>

            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>
<Grid>
    <StackPanel>
    <CheckBox>Hello</CheckBox>
        <CheckBox IsThreeState="True">asdfsdaf</CheckBox>
        </StackPanel>
</Grid>

The best software to modify the existing look and feel of the controls is Expression Blend. If you want to change the existing look and feel and you have to modify the Control Template of the control.

Answer 3

Call me crazy, but I've actually reimplemented standard Aero checkbox in pure XAML. If you want to customize Aero checkbox, it's a good starting point. You can find other styles in my repository on GitHub (specific commit, in case files are moved).

BulletCommon.xaml (common resources for CheckBox and RadioButton)

<ResourceDictionary
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:xx="clr-namespace:Alba.WpfThemeGenerator.Markup">

    <!-- Colors -->

    <!-- Background overlay -->
    <SolidColorBrush x:Key="Bullet.BackgroundOverlay.Hover" Color="#DEF9FA"/>
    <SolidColorBrush x:Key="Bullet.BackgroundOverlay.Pressed" Color="#C2E4F6"/>
    <SolidColorBrush x:Key="Bullet.BackgroundOverlay.Disabled" Color="#F4F4F4"/>
    <!-- Border overlay -->
    <SolidColorBrush x:Key="Bullet.BorderOverlay.Hover" Color="#3C7FB1"/>
    <SolidColorBrush x:Key="Bullet.BorderOverlay.Pressed" Color="#2C628B"/>
    <SolidColorBrush x:Key="Bullet.BorderOverlay.Disabled" Color="#ADB2B5"/>
    <!-- Inner border -->
    <LinearGradientBrush x:Key="Bullet.InnerBorder.Disabled" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#E1E3E5" Offset="0.25"/>
        <GradientStop Color="#E8E9EA" Offset="0.5"/>
        <GradientStop Color="#F3F3F3" Offset="1"/>
    </LinearGradientBrush>
    <!-- Indeterminate inner border -->
    <LinearGradientBrush x:Key="Bullet.InnerBorder.IndeterminateDisabled" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#BFD0DD" Offset="0"/>
        <GradientStop Color="#BDCBD7" Offset="0.5"/>
        <GradientStop Color="#BAC4CC" Offset="1"/>
    </LinearGradientBrush>
    <!-- Inner fill -->
    <LinearGradientBrush x:Key="Bullet.InnerFill.Normal" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#CBCFD5" Offset="0.2"/>
        <GradientStop Color="#F7F7F7" Offset="0.8"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="Bullet.InnerFill.Hover" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#B1DFFD" Offset="0.2"/>
        <GradientStop Color="#E9F7FE" Offset="0.8"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="Bullet.InnerFill.Pressed" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#7FBADC" Offset="0.2"/>
        <GradientStop Color="#D6EDF9" Offset="0.8"/>
    </LinearGradientBrush>
    <!-- Indeterminate fill -->
    <LinearGradientBrush x:Key="Bullet.Fill.Indeterminate" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#2FA8D5" Offset="0.2"/>
        <GradientStop Color="#25598C" Offset="0.8"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="Bullet.Fill.IndeterminateHover" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#33D7ED" Offset="0.2"/>
        <GradientStop Color="#2094CE" Offset="0.8"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="Bullet.Fill.IndeterminatePressed" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#17447A" Offset="0.2"/>
        <GradientStop Color="#218BC3" Offset="0.8"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="Bullet.Fill.IndeterminateDisabled" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#C0E5F3" Offset="0.2"/>
        <GradientStop Color="#BDCDDC" Offset="0.8"/>
    </LinearGradientBrush>

    <!-- Styles -->

    <Style x:Key="Bullet.FocusVisual.Normal">
        <Setter Property="Control.Template">
            <Setter.Value>
                <ControlTemplate>
                    <Rectangle Margin="14,0,0,0" SnapsToDevicePixels="True"
                            StrokeThickness="1" Stroke="{xx:SystemBrush ControlText}" StrokeDashArray="1 2"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <Style x:Key="Bullet.FocusVisual.Empty">
        <Setter Property="Control.Template">
            <Setter.Value>
                <ControlTemplate>
                    <Rectangle Margin="1" SnapsToDevicePixels="True"
                            StrokeThickness="1" Stroke="{xx:SystemBrush ControlText}" StrokeDashArray="1 2"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>

CheckBox.xaml (resources for CheckBox)

<ResourceDictionary
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:xx="clr-namespace:Alba.WpfThemeGenerator.Markup">

    <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="BulletCommon.xaml"/>
    </ResourceDictionary.MergedDictionaries>

    <!-- Colors -->

    <SolidColorBrush x:Key="CheckBox.Stroke" Color="#8E8F8F"/>
    <SolidColorBrush x:Key="CheckBox.Fill" Color="#F4F4F4"/>
    <!-- Check mark -->
    <SolidColorBrush x:Key="CheckBox.Glyph.Stroke.Normal" Color="#FFFFFF"/>
    <SolidColorBrush x:Key="CheckBox.Glyph.Stroke.Pressed" Color="#B2FFFFFF"/>
    <SolidColorBrush x:Key="CheckBox.Glyph.Fill.Normal" Color="#31347C"/>
    <SolidColorBrush x:Key="CheckBox.Glyph.Fill.Pressed" Color="#B231347C"/>
    <SolidColorBrush x:Key="CheckBox.Glyph.Fill.Disabled" Color="#AEB7CF"/>
    <!-- Inner border -->
    <LinearGradientBrush x:Key="CheckBox.InnerBorder" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#AEB3B9" Offset="0.25"/>
        <GradientStop Color="#C2C4C6" Offset="0.5"/>
        <GradientStop Color="#EAEBEB" Offset="1"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="CheckBox.InnerBorder.Hover" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#79C6F9" Offset="0.3"/>
        <GradientStop Color="#79C6F9" Offset="0.5"/>
        <GradientStop Color="#D2EDFD" Offset="1"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="CheckBox.InnerBorder.Pressed" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#54A6D5" Offset="0.3"/>
        <GradientStop Color="#5EB5E4" Offset="0.5"/>
        <GradientStop Color="#C4E5F6" Offset="1"/>
    </LinearGradientBrush>
    <!-- Indeterminate inner border -->
    <LinearGradientBrush x:Key="CheckBox.InnerBorder.Indeterminate" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#2A628D" Offset="0"/>
        <GradientStop Color="#245479" Offset="0.5"/>
        <GradientStop Color="#193B55" Offset="1"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="CheckBox.InnerBorder.IndeterminateHover" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#29628D" Offset="0"/>
        <GradientStop Color="#245479" Offset="0.5"/>
        <GradientStop Color="#193B55" Offset="1"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="CheckBox.InnerBorder.IndeterminatePressed" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#193B55" Offset="0"/>
        <GradientStop Color="#245479" Offset="0.5"/>
        <GradientStop Color="#29628D" Offset="1"/>
    </LinearGradientBrush>
    <!-- Indeterminate highlight -->
    <LinearGradientBrush x:Key="CheckBox.Highlight.Indeterminate" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#80FFFFFF" Offset="0"/>
        <GradientStop Color="#00FFFFFF" Offset="0.5"/>
        <GradientStop Color="#003333A0" Offset="0.5"/>
        <GradientStop Color="#003333A0" Offset="1"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="CheckBox.Highlight.IndeterminateHover" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#80FFFFFF" Offset="0"/>
        <GradientStop Color="#00FFFFFF" Offset="0.5"/>
        <GradientStop Color="#003333A0" Offset="0.5"/>
        <GradientStop Color="#803333A0" Offset="1"/>
    </LinearGradientBrush>
    <LinearGradientBrush x:Key="CheckBox.Highlight.IndeterminatePressed" StartPoint="0,0" EndPoint="1,1">
        <GradientStop Color="#00FFFFFF" Offset="0.5"/>
        <GradientStop Color="#20FFFFFF" Offset="1"/>
    </LinearGradientBrush>

    <!-- Images -->

    <PathGeometry x:Key="CheckBox.Glyph.Geometry">
        <PathFigure StartPoint="9.0, 1.833" IsClosed="True">
            <LineSegment Point="10.667, 3.167"/>
            <LineSegment Point="7, 10.667"/>
            <LineSegment Point="5.333, 10.667"/>
            <LineSegment Point="3.333, 8.167"/>
            <LineSegment Point="3.333, 6.833"/>
            <LineSegment Point="4.833, 6.5"/>
            <LineSegment Point="6, 8"/>
        </PathFigure>
    </PathGeometry>

    <!-- Styles -->

    <Style x:Key="{x:Type CheckBox}" TargetType="{x:Type CheckBox}">
        <Setter Property="FocusVisualStyle" Value="{StaticResource Bullet.FocusVisual.Empty}"/>
        <Setter Property="Foreground" Value="{xx:SystemBrush ControlText}"/>
        <Setter Property="Background" Value="{StaticResource CheckBox.Fill}"/>
        <Setter Property="BorderBrush" Value="{StaticResource CheckBox.Stroke}"/>
        <Setter Property="BorderThickness" Value="1"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type CheckBox}">
                    <BulletDecorator Background="Transparent" SnapsToDevicePixels="True">
                        <BulletDecorator.Bullet>
                            <Grid Width="13" Height="13">
                                <Rectangle x:Name="Background" Margin="0" Fill="{TemplateBinding Background}"/>
                                <Rectangle x:Name="BackgroundOverlay" Margin="0"/>
                                <Rectangle x:Name="InnerFill" Margin="3" Fill="{StaticResource Bullet.InnerFill.Normal}"/>
                                <Rectangle x:Name="InnerBorder" Margin="2" Stroke="{StaticResource CheckBox.InnerBorder}"/>
                                <Rectangle x:Name="Highlight" Margin="3"/>
                                <Path x:Name="GlyphStroke" Margin="0" StrokeThickness="1.5" Data="{StaticResource CheckBox.Glyph.Geometry}"/>
                                <Path x:Name="GlyphFill" Margin="0" Data="{StaticResource CheckBox.Glyph.Geometry}"/>
                                <Rectangle x:Name="Border" Margin="0" Stroke="{TemplateBinding BorderBrush}"/>
                                <Rectangle x:Name="BorderOverlay" Margin="0"/>
                            </Grid>
                        </BulletDecorator.Bullet>
                        <ContentPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" Margin="{TemplateBinding Padding}"
                                VerticalAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                RecognizesAccessKey="True"/>
                    </BulletDecorator>
                    <ControlTemplate.Triggers>

                        <Trigger Property="HasContent" Value="True">
                            <!-- if (HasContent) -->
                            <Setter Property="FocusVisualStyle" Value="{StaticResource Bullet.FocusVisual.Normal}"/>
                            <Setter Property="Padding" Value="4,0,0,0"/>
                        </Trigger>

                        <Trigger Property="IsMouseOver" Value="True">
                            <!-- if (IsMouseOver) -->
                            <Setter TargetName="BackgroundOverlay" Property="Fill" Value="{StaticResource Bullet.BackgroundOverlay.Hover}"/>
                            <Setter TargetName="InnerFill" Property="Fill" Value="{StaticResource Bullet.InnerFill.Hover}"/>
                            <Setter TargetName="BorderOverlay" Property="Stroke" Value="{StaticResource Bullet.BorderOverlay.Hover}"/>
                            <Setter TargetName="InnerBorder" Property="Stroke" Value="{StaticResource CheckBox.InnerBorder.Hover}"/>
                        </Trigger>
                        <Trigger Property="IsChecked" Value="{x:Null}">
                            <!-- if (IsChecked == null) -->
                            <Setter TargetName="Highlight" Property="Stroke" Value="{StaticResource CheckBox.Highlight.Indeterminate}"/>
                            <Setter TargetName="InnerFill" Property="Fill" Value="{StaticResource Bullet.Fill.Indeterminate}"/>
                            <Setter TargetName="InnerBorder" Property="Stroke" Value="{StaticResource CheckBox.InnerBorder.Indeterminate}"/>
                        </Trigger>
                        <Trigger Property="IsPressed" Value="True">
                            <!-- if (IsPressed) -->
                            <Setter TargetName="BackgroundOverlay" Property="Fill" Value="{StaticResource Bullet.BackgroundOverlay.Pressed}"/>
                            <Setter TargetName="InnerFill" Property="Fill" Value="{StaticResource Bullet.InnerFill.Pressed}"/>
                            <Setter TargetName="BorderOverlay" Property="Stroke" Value="{StaticResource Bullet.BorderOverlay.Pressed}"/>
                            <Setter TargetName="InnerBorder" Property="Stroke" Value="{StaticResource CheckBox.InnerBorder.Pressed}"/>
                        </Trigger>
                        <MultiTrigger>
                            <!-- if (IsChecked == null && IsMouseOver) -->
                            <MultiTrigger.Conditions>
                                <Condition Property="IsChecked" Value="{x:Null}"/>
                                <Condition Property="IsMouseOver" Value="True"/>
                            </MultiTrigger.Conditions>
                            <Setter TargetName="Highlight" Property="Stroke" Value="{StaticResource CheckBox.Highlight.IndeterminateHover}"/>
                            <Setter TargetName="InnerFill" Property="Fill" Value="{StaticResource Bullet.Fill.IndeterminateHover}"/>
                            <Setter TargetName="InnerBorder" Property="Stroke" Value="{StaticResource CheckBox.InnerBorder.IndeterminateHover}"/>
                        </MultiTrigger>

                        <MultiTrigger>
                            <!-- if (IsChecked == null && IsPressed) -->
                            <MultiTrigger.Conditions>
                                <Condition Property="IsChecked" Value="{x:Null}"/>
                                <Condition Property="IsPressed" Value="True"/>
                            </MultiTrigger.Conditions>
                            <Setter TargetName="Highlight" Property="Stroke" Value="{StaticResource CheckBox.Highlight.IndeterminatePressed}"/>
                            <Setter TargetName="InnerFill" Property="Fill" Value="{StaticResource Bullet.Fill.IndeterminatePressed}"/>
                            <Setter TargetName="InnerBorder" Property="Stroke" Value="{StaticResource CheckBox.InnerBorder.IndeterminatePressed}"/>
                        </MultiTrigger>
                        <MultiTrigger>
                            <!-- if (IsChecked == true && IsPressed) -->
                            <MultiTrigger.Conditions>
                                <Condition Property="IsChecked" Value="True"/>
                                <Condition Property="IsPressed" Value="True"/>
                            </MultiTrigger.Conditions>
                            <Setter TargetName="GlyphStroke" Property="Stroke" Value="{StaticResource CheckBox.Glyph.Stroke.Pressed}"/>
                            <Setter TargetName="GlyphFill" Property="Fill" Value="{StaticResource CheckBox.Glyph.Fill.Pressed}"/>
                        </MultiTrigger>
                        <MultiTrigger>
                            <!-- if (IsChecked == true && !IsPressed) -->
                            <MultiTrigger.Conditions>
                                <Condition Property="IsChecked" Value="True"/>
                                <Condition Property="IsPressed" Value="False"/>
                            </MultiTrigger.Conditions>
                            <Setter TargetName="GlyphStroke" Property="Stroke" Value="{StaticResource CheckBox.Glyph.Stroke.Normal}"/>
                            <Setter TargetName="GlyphFill" Property="Fill" Value="{StaticResource CheckBox.Glyph.Fill.Normal}"/>
                        </MultiTrigger>

                        <Trigger Property="IsEnabled" Value="False">
                            <!-- if (!IsEnabled) -->
                            <Setter Property="Foreground" Value="{xx:SystemBrush GrayText}"/>
                            <Setter TargetName="InnerFill" Property="Fill" Value="{x:Null}"/>
                            <Setter TargetName="GlyphStroke" Property="Stroke" Value="{x:Null}"/>
                            <Setter TargetName="BorderOverlay" Property="Stroke" Value="{StaticResource Bullet.BorderOverlay.Disabled}"/>
                            <Setter TargetName="InnerBorder" Property="Stroke" Value="{StaticResource Bullet.InnerBorder.Disabled}"/>
                        </Trigger>
                        <MultiTrigger>
                            <!-- if (IsChecked == null && !IsEnabled) -->
                            <MultiTrigger.Conditions>
                                <Condition Property="IsChecked" Value="{x:Null}"/>
                                <Condition Property="IsEnabled" Value="False"/>
                            </MultiTrigger.Conditions>
                            <Setter TargetName="InnerFill" Property="Fill" Value="{StaticResource Bullet.Fill.IndeterminateDisabled}"/>
                            <Setter TargetName="InnerBorder" Property="Stroke" Value="{StaticResource Bullet.InnerBorder.IndeterminateDisabled}"/>
                        </MultiTrigger>
                        <MultiTrigger>
                            <!-- if (IsChecked == true && !IsEnabled) -->
                            <MultiTrigger.Conditions>
                                <Condition Property="IsChecked" Value="True"/>
                                <Condition Property="IsEnabled" Value="False"/>
                            </MultiTrigger.Conditions>
                            <Setter TargetName="GlyphFill" Property="Fill" Value="{StaticResource CheckBox.Glyph.Fill.Disabled}"/>
                        </MultiTrigger>

                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>

Notes:

1. {xx:SystemBrush ControlText} is a shortcut for {DynamicResource {x:Static SystemColors.ControlTextBrushKey}}. You can either use that shortcut or just find and replace with regex.

2. RTL, animations, weird cases are not supported.

3. This style is slower than using BulletChrome which is heavily optimized.