Simple Partition Grid Demo
This demo shows how to create a simple PartitionGrid that will be used by
the hierarchic layout algorithm.
The information about the desired position of a node in the partition 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 partition grid.