Balloon layout requires a tree or a collection of trees as its input.
The tree will be routed in a quasiradial style which we call balloon style.
This is a good choice for undirected, dense, or huge trees with a high number
of nodes on a single hierarchy level. Note: If the input is a general graph (not a tree),
the layout is applied to a spanning tree of the graph.
General Tab
Root Node Policy
Determines which node should be used as root of the tree.
 Directed Root

Chooses a node with indegree zero, if present.
A good choice for directed rooted trees.  Center Root

Chooses the root such that the depth of the resulting tree
gets minimized.  Weighted Center Root

Chooses the root such that the number of paths between any two nodes that
traverse the root is maximal.
This seems to be a natural root for undirected trees.
Routing Style for NonTree Edges
Determines the routing style for all nontree edges if the input graph is a general graph (not a tree).
(Note: Tree and nontree edges are determined automatically.)
 Organic
 Organic routing.
 Orthogonal
 Orthogonal routing.
 StraightLine
 Straightline routing.
 Bundled

Bundled routing. Edge paths will be routed such that the common parts of different edges are to
some degree merged into a bundled part.
Act on Selection Only
Whether or not to act on selected nodes and edges that are connected
to selected nodes only.
Preferred Child Wedge
This setting determines the angular range of the sector that will be reserved
for the children of a node. The possible angluar range lies between
1 and 359. The remaining angular range (360x) will be automatically used
to accommodate the edge that connects to the root node.
The smaller the chosen value, the more one will gain the impression that
the nodes drive away from their root nodes and the center of the graph.
Generally speaking, the compactness of the layout will decrease with smaller
values. Very small values will lead to layouts that consume a lot of space.
Preferred Root Wedge
This setting determines the angular range of the sector that will be reserved
around the root node of the graph to accommodate the attached subtrees.
Minimal Edge Length
Determines the minimal length of an edge.
Compactness Factor
This parameter influences the length of the treeedges as it is computed
by the layouter. The smaller the compactness factor, the shorter the
treeedges and the more compact the overall layout. The bigger the compactness factor
the more difficult, and hence slower, the layout computation.
Allow Overlaps
If activated, this option further increases compactness of the resulting layout
but may introduce slight node overlaps.
Use Drawing As Sketch
If activated, the original circular order of child nodes
around each parent node will be maintained.
Place Children Interleaved
If activated, the children (successors) of each node in the tree will possibly be placed in an interleaved
fashion, i.e., such that the successors of a node are placed at different distances in an alternating way.
Enabling this option may produce more compact results for large graphs.
Note that if there is enough space within the desired child wedge of a node all children may
be placed without interleaving.
Straighten Chains
Specifies whether chains within the graph shall be drawn straight or not. Straightening all chains may lead
to smoother, more symmetric results.
Bundling strength
Determines how tightly the edges are merged/bundled for Routing Style for
NonTree Edges Bundled
. The higher this value, the stronger
the connection of the bundled edges.
Labeling Tab
Place Edge Labels
If activated, edge labels will be placed by the layout algorithm.
Note that this option only works for edge labels with a free edge label model.
Hence, all edge labels automatically receive such a model.
Node Labeling
Specifies how to place node labels.
 None
 Automatic node labeling is deactivated.
 Horizontal

All node labels are placed horizontally centered on the corresponding node.
There will be no overlaps between node labels and other graph elements.  Raylike at Leaves

Node labels of leaf nodes get the same orientation as the nodes’ incoming edge.
These labels will be placed outside the node. Note that this style can only be applied to node labels
having a free node label model. Hence, all node labels automatically receive such a model.
There will be no overlaps between node labels and other graph elements.  Consider Position

The algorithm considers the current position of the node labels, i.e., the node labels keep their relative position
and do not overlap with other graph elements.
AutoFlip Node Labels
If activated, node labels will be automatically flipped if they would be upsidedown.