QSizePolicy::Fixed and QGraphicsLayoutItem - confusion

[Asperamanca]

When I use QGraphicsLayouts, and SizePolicy "fixed", which of the sizeHints is actually used?

In the enum QSizePolicy::Policy, the policy "Fixed" is described as:

bq. The QWidget::sizeHint() is the only acceptable alternative, so the widget can never grow or shrink (e.g. the vertical direction of a push button).

However, for a QGraphicsLayoutItem, no sizeHint() exists - the overload requires that a specific sizeHint (either minimum, maximum or preferred) is returned.

In consequence, if I want to use the "Fixed" policy, do I

• just set the preferred size, or
• set minimum and maximum size, or
• set minimum, maximum AND preferred size
  ?