public ListChangeListener.Change<TreeItem<DocumentProperty>> changeEvent() {
        return changeEvent;
    }
An event that is published when the user selects a new span
of nodes in the "Project Tree" section. This can be used to
add additional items to the workspace from a plugin.

@author  Emil Forslund
@since   2.2.0
tool-parent/tool-core/src/main/java/com/speedment/tool/core/event/TreeSelectionChange.java