How to Add a Container (Row or Column)

1. Make sure Show Merge / Split Tools is active
2. Mouse over the most bottom / top side of a Section and click + Add Section button to add a new row / section under / above the current row / section
3. Mouse over the most left / right side of a Section and click + Add Container button to add a new container / column to the left / right side of the Section
4. Mouse over the most bottom/ right side of a Container and click + Add Row / Add Column button to split this container horizontally / vertically