nodeMinHeight

Each subclass should override this, to calculate the minimum height it requires. In general, do not call this, and instead call evalMinHeight.

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

The default implementation returns 0.

The actual height of the node is determined by its parent, which may ignore this node's requirements.

• The root node of a scene is always the size of the window's client area, and therefore can be smaller than the minimum. This often causes nodes further down the tree of nodes to be squashed below their minimums too.

• Split pane ignores its children's minimums.