event.detail= DND.DROP_COPY;
event.detail= TypeHierarchyTransferDropAdapter.OPERATION;
	public void validateDrop(Object target, DropTargetEvent event, int operation) {		event.detail= DND.DROP_NONE;		initializeSelection();		if (target != null){			super.validateDrop(target, event, operation);			return;		}			if (getInputElement(getSelection()) != null) 			event.detail= DND.DROP_COPY;	}