ConfirmPosition returns true if there is a tree at position tp of argument tree.

FirstChildPosition returns the IPos corresponding to the first child of tp, or nil if there are no children.

LastChildPosition returns the IPos corresponding to the last child of tp, or nil if there are no children.

LastDescendant moves to the last child of the current level, and then to the last child of that node, and onwards until the end is reached.

LastInDirection navigates the tree starting at tp and moving in the direction determined by the function f until the end is reached.

NextOfKin returns the position of the sibling of the parent of tp if that position exists, and if not, the sibling of the parent's parent, and on upwards.

NextPosition is used to navigate the tree in a depth first manner.

NextSiblingPosition returns the position of the next sibling relative to the position tp.

ParentPosition returns the position of the parent of position tp or nil if tp is the root node.

PreviousPosition is used to navigate the tree backwards in a depth first manner.

PreviousSiblingPosition returns the position of the previous sibling relative to the position tp.

CacheKey tracks content for a given tree and its expansion state.

For callback registration.

TreePos is a simple implementation of IPos.

WidgetCallback is a simple struct with a name field for IIdentity and that embeds a WidgetChangedFunction to be issued as a callback when a widget property changes.

IPos is the interface of a type that represents the position of a sub-tree or leaf in a tree.