Add checkbox to ComboboxItem
===

I want to a one or two checkboxes in my combobox (like microsoft word) ![enter image description here][1].

I put my checkbox in a separate Combobox Item, and set them item disabled. (I dont want that a user can select this item). But the checkbox is always disabled.
![enter image description here][2]

Is there another solution?

That's my code:

		<ComboBox Height="36">
			<ComboBoxItem Height="36">
				<Grid>
					<Grid.ColumnDefinitions>
						<ColumnDefinition Width="30"/>
						<ColumnDefinition Width="*"/>
					</Grid.ColumnDefinitions>
					<Grid Grid.Column="1">
						<Grid.RowDefinitions>
							<RowDefinition Height="16" />
							<RowDefinition Height="16" />
						</Grid.RowDefinitions>
						<TextBlock Text="Item Title 1" Grid.Row="0" FontWeight="Bold" />
						<TextBlock Text="Item Description 1" Grid.Row="1" FontStyle="Italic" />
					</Grid>
				</Grid>
			</ComboBoxItem>
			<ComboBoxItem Height="36">
				<Grid>
					<Grid.ColumnDefinitions>
						<ColumnDefinition Width="30"/>
						<ColumnDefinition Width="*"/>
					</Grid.ColumnDefinitions>
					<Grid Grid.Column="1">
						<Grid.RowDefinitions>
							<RowDefinition Height="16" />
							<RowDefinition Height="16" />
						</Grid.RowDefinitions>
						<TextBlock Text="Item Title 2" Grid.Row="0" FontWeight="Bold" />
						<TextBlock Text="Item Description 2" Grid.Row="1" FontStyle="Italic" />
					</Grid>
				</Grid>
			</ComboBoxItem>
			<ComboBoxItem Height="25" IsEnabled="False">
				<Grid>
					<Grid.ColumnDefinitions>
						<ColumnDefinition Width="30"/>
						<ColumnDefinition Width="*"/>
					</Grid.ColumnDefinitions>
					<Grid Grid.Column="1">
						<CheckBox IsChecked="false" HorizontalAlignment="Left" Width="16" Height="16" IsEnabled="True" />
						<Label Margin="10 0 0 0" HorizontalAlignment="Left" Content="I'm a checkbox ;)" />
					</Grid>
				</Grid>
			</ComboBoxItem>
		</ComboBox>


  [1]: http://i.stack.imgur.com/wB8AI.png
  [2]: http://i.stack.imgur.com/kyg7G.png