NGroupingHeader Class Methods

	Name	Description
	ArrangeContent	Overridden. Overriden to layout the content.
	MeasureContent	Overridden. Overriden to measure the content.
	OnRemoveButtonClick	Called when the remove button is clicked. This implementation removes the grouping rule represented by this header.
	OnSortingButtonClick	Called when the sorting button is clicked. This implementation toggles the sorting direction of the grouping rule.