JavaFX Tutorial part6 How to use GridPane

GridPane is useful container for layout design. addColumn() method places the nodes vertical direction. it will put a node by increasing 1 row index while holding the column index fixed. addRow() method places the nodes horizontal direction. it will put a node by increasing 1 column index while holding the row index fixed. span must be 1 or above because it is length of column or row. For example, column span of 2 means the number of column index a node can take is 2.