'host' permissions were added in Version 4.1 to overcome a specific problem when using Navigate Up WE in Chrome (Note: the Navigate Up WE source code is the same for both Firefox and Chrome).

This problem has been resolved and the 'host' permissions have been removed in Version 4.2. The permissions are now the same as in Version 4.0 and earlier versions.

There are a few special Firefox and Chrome pages that Navigate Up WE and many other WebExtensions (WE) add-ons cannot work with.

This applies to all pages on Mozilla Add-ons pages and to all “about:” pages.

"English only..." - For traditional add-ons, developers could use the free BabelZilla web-based translation management system to coordinate submissions from volunteer translators. At present, for WebExtensions add-ons, there is no equivalent web-based translation management system.

"Only 3 items..." - The toolbar button right-click menu can only allows a maximum of 6 add-on menu items. If you want to see 6 URL levels on this menu, you can disable the 'Navigate Up One Level' and 'Navigate Up To Root' menu items. Note, the 'Navigate Up WE' submenu on the normal context menu shows all available URL levels.

"Why to move out of address bar..." - For compatibility with the Chrome version and because several users requested this change. It would be possible to have an option to place the button in the address bar instead of on the toolbar.