Simple Layout Grid Demo
This demo shows how to create a simple LayoutGrid that will be used by the
hierarchical layout algorithm.
The information about the desired position of a node in the layout grid is stored in its
tag and also appears in its label. The first digit represents the row index and the second
the column index.
The layout algorithm will calculate the positions of the nodes based on this information
such that the nodes are assigned to the correct cell of the layout grid.