It’s the legacy tray. Gnome 3.16 uses it for some months. What’s wrong with it?
You can’t change its position so it’s always behind the dock (dash to dock extension), it feels completely divorced from the rest of the Gnome environment… it’s just tacked on there and feels like an afterthought. And you need a workaround (which pretty much most of the shell extensions are at this point) to get rid of it apparently. It basically makes sense only if you’re happy with the default Gnome setup, and it tramples on the “oh, but you can customize it any way you want” mantra that every Gnome user starts their morning with to live with the “we know better than you” design choices.
And try getting rid of it while retaining access to those tray items. Someone wrote “an extension” for this purpose, which places the icons on the top bar. Easy enough –– if you’re willing to live with the top bar that is; because this particular extension conflicts with the only available extension that let’s you hide the top bar. So, you can’t get rid of the legacy tray and still have access to those tray icons while not having the top bar visible at all times. It’s like a distant cousin to the dependancy hell but now in the context of your DE.
That’s what’s wrong with it.
Anyway, thanks for the reply. Much appreciated.