The complexity of the class InformationPanel has grown a lot from KDE 4.0 to KDE 4.3. One main reason is that a lot of things are done now asynchronously with timers to prevent a blocking UI and unnecessary expensive operations.
To keep the Information Panel maintainable and prepared for future features a cleanup has been done. The whole user interface handling has been moved into the class InformationPanelContent that offers a straight forward interface: showItem(const KFileItem& item) and showItems(const KFileItemList& items).
The class InformationPanel is responsible for calling those methods in a way that hovering items, changing directories, doing selections, rename and delete operations, ... don't result in calling showItem() 10 times per second.