Represents a composite callout. Composite callouts are a filled background along with an optional shadow, which is placed
behind text. They may also have a leader line (consisting of one or both of a simple line, and filled dart)
connecting the callout to an anchor point. Composite callouts may have additional surrounding text elements.
The text representing these parts is specified in the text string using tags. Their relative position properties are
specified in the CIMCompositeCallout through their corresponding CIMCompositeTextPartPosition elements specified below,
but these properties can also be overridden with tag attributes.
Target Platforms: Windows 10, Windows 8.1