Hi there I really liked the look of this extension when I installed it today, but when I restarted, FF lost my custom toolbar. I recreated it and restarted FF, but it disappeared again. I removed this extension and repeated this process, and the toolbar persisted. I installed the extension, and the toolbar disappeared.
Hence, I'm afraid to conclude I think it is causing these issues. I will update this review in the next couple of weeks if I discover that the toolbar disappears again without the extension installed.
Good effort tho! I will increase my rating to 5 if it transpires that the bug exists elsewhere.