One of my favourite addons, Puntuado con 5 de 5 estrellas
using it for a very long time.
No more loose windows, everything is easily accessible in the same sidebar - fully customizeable to your prefernces.
With the sidebar you can organize and launch your bookmarks, check your addons, manage your downloads or whatever needed.
Previous issues have been fixed with the current version 0.7.9.
This is well done and should match everyones taste.