I have very very very very very rarely seen an Addon made with so few care and attention and love.
It feels like a bored programmer @Mozilla decided to do this instead of smoking his cigarette.
No way to decide if this thing has to be always visible or not (it is always there, HORRIBLE and so OLD SCHOOL).
It feels, looks, works like something from the 80's.
Very very very very very very very bad.

OMFG!!!!
I have just read that this horrible disgraceful thing was made with the collaboration of several universities AND public funds!!!!!!!!!!!!!
If this is the best that modern universities can do, then humanity is lost.