public boolean isCellEditable(int row, int col) {
	        //Note that the data/cell address is constant,
	        //no matter where the cell appears onscreen.
	        if ((col > 0) && tableData[row][col]!=null && row < tableRows-1) {
	            return true;
	        } 
	        else if(tableData[row][col] == null && (row == 0 || tableData[row-1][col] != null)) {
	        	return true;
	        }
	        return false;
	    }