Assegnate 5 su 5 stelle

FF32, Ubuntu 14.04
In some sites such as Gmail, after scrolling (either using the mouse wheel or keyboard arrows) the bar disappears...

PS. This does not happen on every site or everytime.

I've been using this add-on for ages, this is the first time I've encountered a problem...

Questa recensione riguarda una versione precedente (3.0.5) del componente aggiuntivo. 

If you want to help me to solve this bug, see the support forum discussion that is begining : http://forums.mozillazine.org/viewtopic.php?p=13751999#p13751999