detail are specializations → how can I do that, while the dataview doesn’t support specializations?
Dataview does indeed not have the option like listview and template view to assign a specific per specialization. Raise an idea for it, maybe in a future release it will get incorporated. Meanwhile, a workaround solution is to fill the dataview with a templateview having the datasource restricted to only the object of the dataview and assign specialization specific templates to the the templateview.
when the users selects another item, he leaves the c ….
No idea, my best guess would be using javascript by adding the HTML-widget to your page and make that javascript adding a OnLoseFocus to some element.