It's really a way to combat a fairly common graphic bug where the hover info never disappeared. Maybe when the game is further developed or is requested enough times, then a new UI may be implemented or the old one would be restored.
To achieve two step hovers, you need to keep the first opened window for a while, to be able to leave the hovered item and hover the opened window again. So there is a timeout on each hover window to be disappeared. This also cause another annoying issue. even on every tile of the map mouse hover gives you an info. You need to wait for it to get closed to reach if anything below it. That is also causing the hover bug. On some situations timeout resets and the hover window never be closed again. To fix this you need to open another "type" of that window. That system is totally annoying for me... Forget the names just open the info window...