Minor annoyance Rated 4 out of 5 stars
Much needed add-on!
A buglet: When a FF page is partially overlapped by another page, a tooltip can be elicited from the FF page by moving the cursor over it. If the elicited FF tooltip overlaps the partially covering other page -- perhaps because the cursor had not ventured very far onto the FF page -- it (the FF tool-tip) will remain even after the cursor has left the FF page. This Cheshire tooltip can be removed by running the cursor over it.
Otherwise, a great addition!