QTreeWidget::ChildIndicatorPolicy prevents programmatic expansion of nodes

[milgner]

After setting the ChildIndicatorPolicy of a QTreeWidget to QTreeWidgetItem::DontShowIndicator, it does not only hide the indicator but also the children and even prevents programmatic expansion of the nodes using setExpanded(true).
What I would like to achieve is to not only hide the indicator (can be done using stylesheet, too) but to prevent users from collapsing the nodes, i.e. to have a tree view where all nodes are expanded at all times.