DataGridColumnHeadersPresenter.GetLayoutClip Method (Size)
Returns a geometry for a clipping mask. The mask applies if the layout system attempts to arrange an element that is larger than the available display space.
Assembly: PresentationFramework (in PresentationFramework.dll)
This method override always returns a clipping geometry that is the same size as the column header, regardless of the ClipToBounds property value.
Available since 4.0