insertChild

Inserts child as a direct child of this node at the given index, shifting any existing children at and after index one position to the right.

index

the position at which to insert child; must be in 0..children.size.

child

a node that is not already attached to a tree. To move a node that already has a parent, call detach on it first.

if index is out of range.

if child already has a parent, or if attaching it here would create a cycle (i.e. child is this node or one of its ancestors).