It seems good, but I do not see any keyboard shortcut for opening/closing it like with regular side bars. It would be nice if that was added to either the add-on or the add-on's description.
According to this: https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/sidebarAction/open Shortcuts not supported yet. This is nothing i can do until guys from Mozilla finish SidebarAction API.
