<local:ColumnFilterCell x:Class="CustomFilterRow_WPF.BooleanColumnHeader"
						xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
						xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
						xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
						xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
						mc:Ignorable="d" 
						xmlns:local="clr-namespace:CustomFilterRow_WPF"
						d:DesignHeight="300" d:DesignWidth="300">
	<Border>
		<CheckBox IsThreeState="True"
				  VerticalAlignment="Center"
				  Checked="OnCheckBoxStateChanged" 
				  Unchecked="OnCheckBoxStateChanged" 
				  Indeterminate="OnCheckBoxStateChanged"
				  IsChecked="{x:Null}"/>
	</Border>
</local:ColumnFilterCell>