<DataSource	ID="Spacer" inheritsFrom="Canvas" Constructor="LayoutSpacer" 
            showLocalFieldsOnly="true" showSuperClassActions="false">
    <fields>
		<field name="width"				type="measure" title="Width"/>	
		<field name="height"			type="measure" title="Height"/>
		<field name="visibility"		type="visibilityEnum" title="Visibility"/>	

        <!-- turn off these fields so you can't DnD into them in VB -->
		<field name="children"		type="Canvas" multiple="true"	propertiesOnly="true" 
               inapplicable="true"/>
		<field name="peers" type="Canvas" multiple="true" propertiesOnly="true" 
               inapplicable="true"/>
    </fields>
</DataSource>