- big welcome to the forum, nice to have you with us.
Its not an app/widget/viewer I'm familiar with............
Firstly, have you tried logging out and back in again to see whether it's still there?
If you right click (or hover the mouse) on top of the "mysterious"
viewer does it show a name and/or description? if it does what is it?
Have you installed anything from Synaptic or added any Widgets - if you have what were they?.
If it's a widget you may
need to unlock them before it will allow it to be removed