In the navigation pane, hovering over an item highlights it. Navigating to a table highlights the table to show that it's the active item, this works as expected. Navigating to a database (while the main pane is in the database view) highlights all tables in that database as well as the database itself. I think it should only highlight the database.
Adding second attachment
IMO, it is the expected behavior, as when a database is expanded(and selected), whole of it is highlighted, when collapsed, only the database item is highlighted. It was to distinguish the selected(and expanded) database area from other expanded(but not selected) databases.
I tend to agree with Atul, mostly because it does not seem to be easy to fix without some alterations to the structure of the nativation ;)
Both behaviors can be expected by some users but I favor the status quo.