I like IceDragon a lot and recommend it to friends and family. However, it seems to have an annoying bug. About 2 or 3 times per month the Bookmarks toolbar will disappear. It happened again a few days ago. Sometimes, the space will be there below the Navigation toolbar, it it is blank.
I then have to either use the View menu to restore it, or right-click on a toolbar and uncheck Bookmarks toolbar, then check Bookmarks toolbar again and then it is restored.