Well I have a funny problem. I'm using Firefox 23.0.1 and suddenly the Horizontal Nav bar disappears if you scroll down the page. For Example, Here is what it looks like when I go to a page here,
Now if I scroll two or more lines down, instead of the the panel waiting till I've got past it to re-pin, it just disappears.
The weirdest thing is, if I go to the bottom of the page & click on reload, the side nav panel shows up again and works like you intended to as long as I stay on that page. Hmmmm.....