<StackPanel xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
		<CheckBox IsChecked="False" Content="Nie zaznaczony" IsThreeState="True"/>
    <CheckBox IsChecked="True" Content="Zaznaczony" IsThreeState="True"/>
    <CheckBox IsChecked="{x:Null}" Content="Null"   IsThreeState="True"/>
    <StackPanel.LayoutTransform>
        <ScaleTransform ScaleX="2" ScaleY="2"/>
    </StackPanel.LayoutTransform>

	</StackPanel>