Support or disable "insert" for drag/drop wxDataViewCtrl on OSX

see #18167

include/wx/dataview.h

@@ -846,7 +846,8 @@ public:
         m_dataBuffer(event.m_dataBuffer),
         m_dataSize(event.m_dataSize),
         m_dragFlags(event.m_dragFlags),
-        m_dropEffect(event.m_dropEffect)
+        m_dropEffect(event.m_dropEffect),
+        m_proposedDropIndex(event.m_proposedDropIndex)
 #endif
         { }
 
@@ -889,6 +890,10 @@ public:
     int GetDragFlags() const { return m_dragFlags; }
     void SetDropEffect( wxDragResult effect ) { m_dropEffect = effect; }
     wxDragResult GetDropEffect() const { return m_dropEffect; }
+    // for plaforms (currently only OSX) that support Drag/Drop insertion of items,
+	// this is the proposed child index for the insertion
+	void SetProposedDropIndex(int index) { m_proposedDropIndex = index; }
+	int GetProposedDropIndex() const { return m_proposedDropIndex;}
 #endif // wxUSE_DRAG_AND_DROP
 
     virtual wxEvent *Clone() const wxOVERRIDE { return new wxDataViewEvent(*this); }
@@ -928,6 +933,7 @@ protected:
 
     int                 m_dragFlags;
     wxDragResult        m_dropEffect;
+    int                 m_proposedDropIndex;
 #endif // wxUSE_DRAG_AND_DROP
 
 private: