Rated 5 out of 5 stars

Great addon.
I have the left main sidebar set to autohide and it works fine but after a firefox restart it will only open 1/8 inch.
I did a full computer restart and it is working now.
RightSidebar/TwinSidebar functions perfectly.
Could you please add an option for a third sidebar to open on the top while the other two can also be opened with different sidebars at the same time.
I used to use multisidebar and it is discontinued now.

This review is for a previous version of the add-on ( 

I doubt I will add a third sidebar on top soon (unless I get bored enough), the reason for this, besides two sidebars being a big ordeal already, is that a top sidebar would be very different from the other two. While the current twin sidebar is just a copy on the other side, one on top or the bottom would require an extensive customization work to be properly displayed. Most sidebars from add-ons, and even the native firefox sidebars, are constructed with being on the side in mind. Thanks for liking the add-on, I just wanted to say that you shouldn't hold your breath for a feature like this.