efine custom policies for a tree node or policies can be combined. The goal of this article is not to explore these features in depth. If you are interested in all the features available to developers, the following are good places to start:

<b>Articles</b>
- The \ref page_observer_widgets article.
- The \ref subject_filters section of the \ref page_observers article.

<b>API Documentation</b>
- Qtilities::Core::ObserverHints
- Qtilities::Core::Observer which is the base class of tree nodes and does all th