By default CombineElementWithPenAndBrush is false and this means that only elements that have only pen or only brush set are defined. If an element had both pen and brush defined it is not combined. This prevents problems when elements are overlapping - elements in front can cover some part of background elements. If CombineElementWithPenAndBrush is set to true, than such elements are combined which leads to better performance, but can produce some anomalies if elements are overlapping. NOTE: CombinePreserveElementsOrder is used only when CombineGeometries is set to true.

public bool CombineElementWithPenAndBrush { get; set; }