Gets or sets a converter to apply to the property value or the item to produce the final value that is used to determine which group(s) an item belongs to.
Assembly: PresentationFramework (in PresentationFramework.dll)
If you want to change the value that is eventually used for group you can use the property to supply a value converter. For example, you may want to group items based on the first letter of a name. If the PropertyName property is not set, the item itself is passed to the value converter. The converter may return a collection, which indicates the items can appear in more than one group.