While "hiding" the tabs that aren't used has been implemented, the empty space that the tabs would have taken up is still there, and it leaves an ugly bar.
While focusing on a chat tab, the 'close' button for the tab at the very end is now cut off; this might be because the width now almost supports eleven tabs, but not quite. Additionally, the tabs in the second (and possibly upper rows) don't unhide to the full height, as seen by the ugly bar that is still present.
I also don't think hiding the tabs serves much purpose.