The image below shows the dialog:
Three styles are available :
Three styles are available, the default is Cyclic. The other two arrange nodes inside the main circles in a more compact way which looks nicer but takes longer to layout.
Determines the minimal length of an edge that connects two nodes that lie on separate circles (tree-edges). The smaller the chosen value, the more compact the resulting layout.
Whenever tree edges connect to a node that lies on a circle together with other nodes, the layouter tries to direct that edge in such a way that its prolongation crosses through the center of the circle. This is not always possible though, for example, if more than one tree-edge connect to the same circle node. This parameter determines the allowed angular deviation from the optimal edge direction as described above. The bigger the chosen value, the more compact the resulting layout. If a value smaller than 90 degrees is chosen, then the tree-edges might cross through the circular arranged components.
This parameter influences the length of the tree-edges as it is computed by the layouter. The smaller the compactness factor, the shorter the tree-edges and the more compact the overall layout. The bigger the compactness factor the more difficult, and hence slower, the layout computation.