public Object getTransferData(DataFlavor flavor)  
                                 throws UnsupportedFlavorException {  
            if(!isDataFlavorSupported(flavor))  
                throw new UnsupportedFlavorException(flavor);  
            Card[] cards = new Card[nodes.length];
            for (int i = 0; i < nodes.length; i++) {
            	if (nodes[i].isLeaf()) {
            		cards[i] = (Card) nodes[i].getUserObject();
            	}
            }
            return cards;
        }