This is not a bug in APL or header, but in the gallery. The APL currently does nothing with the PageHeader when changing the layout, the apps need to deal with that. The gallery does that by setting and unsetting the PageHeader.flickable property, but that does not automatically reset PageHeader.exposed when the flickable is set or unset.
This can be a feature that we add to the APL. We would need some UX input for that to describe what should happen exactly when changing the layout. That would be a separate bug though.
This is not a bug in APL or header, but in the gallery. The APL currently does nothing with the PageHeader when changing the layout, the apps need to deal with that. The gallery does that by setting and unsetting the PageHeader. flickable property, but that does not automatically reset PageHeader.exposed when the flickable is set or unset.
This can be a feature that we add to the APL. We would need some UX input for that to describe what should happen exactly when changing the layout. That would be a separate bug though.