[DefaultValue(50)]
public double LayerSpacing {get; set;}

Property Value

This is the distance between a parent node and its first row of children, in case there are multiple rows of its children. The RowSpacing property determines the distance between rows of children. Negative values may cause children to overlap with the parent.

This sets the RootDefaults's property of the same name.

Reference

TreeLayout Class
TreeLayout Members
LayerSpacingParentOverlap Property