As Fernanernie said, it's a pulldown menu to see your favorites and notifications. After you slide it down, If you hold your finger on one of the 4 options on that screen for 2 seconds or so, it will open up the screen to manage your favorites - then you can hold your finger on any additional features in the top row for a few seconds and then drag it down into the favorites row below to replace the defaults.
Even though this video I found is not from a Taos, I have confirmed on my Taos that the managing favorites functionality is pretty much the same, albeit with a few less options than what is shown.