nodePrefHeight

Each subclass of node can determine its preferred height. As most nodes are composed of smaller nodes, this is typically calculated using evalPrefWidth of the child nodes, with extra added for spacing, padding and borders.

This can be overridden on an ad-hoc basis using overridePrefHeight.

However, the final width of the node is determined by its parent, which may ignore both of these. (e.g. if the parent is too small to accommodate all of its children).