MapOverlay should be made available in ArcGIS Quartz liberary. It is not currently available in v100.0.0 as of yet and there is no equivalent of
onPaint(Graphics g) in 100.0. Main benefit of
onPaint(Graphics g) in
MapOverlay was the ability to capture mouse events and draw anything directly over the map. IMO, this was a great functionality and should be made available in the latest ArcGIS Quartz release also.