I have the following horizontal layout (size hints in curly braces, {min,pref,max})

| - [A:{11,84,84}] - [B{75,75,16777215}] - |

size policy of A: QSizePolicy::Expanding
size policy of B: QSizePolicy::Preferred

When the layout is made wider, only the Expanding item will grow. As soon as the Expanding item has reached its limit, it will distribute space between the items instead of growing item B.

This causes things to break such as QTBUG-25801, because other code paths of the layouts system expects that all expanding or growing items will grow to their fullest.