Looks like your quickslots.
So check your quickslot related addons.
Greymind quickslot bar
or
AUI
or Bandits user Interface maybe
You can find out yourself:
You must enable the setting at "Social" -> Show mouse cursor during typing
Move the mouse above the control, leave it there, type (copy and paste) into chat:
Code:
/script d(tostring(moc():GetName()))
It should show you the name of the control in the chat then so you could know by the name what addon it belongs to