many changes :P

mapview/model/MapModelElement.h

@@ -5,6 +5,7 @@
 #include "MapLayer.h"
 
 class MV2DElement;
+class MV3DElement;
 
 class MapModelElement {
 
@@ -21,10 +22,13 @@ public:
 	virtual ~MapModelElement() {;}
 
 	/** get the 2D interaction class for this element */
-	virtual MV2DElement* getMV2D() const = 0;
+	virtual MV2DElement* getMV2D() const {return nullptr;}
+
+	/** get the 3D interaction class for this element */
+	virtual MV3DElement* getMV3D() const {return nullptr;}
 
 	/** delete this element from the model */
-	virtual void deleteMe() const = 0;
+	virtual void deleteMe() const {;}
 
 	/** get the parent element */
 	MapLayer* getParent() const {return parent;}