* Set parent of title- and content-widget to associated container-widget
* inside FloatingWidget::takeContent(...)
Restore state
* Restore all contents as visible and then call hideSectionContent(...) at
* the end. This is more consistent and uses same code (public API).
* Pass version to sub-methods to handle different formats
* Fix serialization, if nothing is visible (no sections, only hidden
* contents)
Updates SectionContent API: Its only possible to use it as shared pointer
(RefPtr), Copies not possible.
Handle missing or too many content references in restore procecure.
