Tab Open/Close Control автор F. Kolbe

btw:
about:config -> browser.tabs.insertRelatedAfterCurrent -> true
about:config -> browser.tabs.selectOwnerOnClose -> true

open the new tab:
left, right, first, last, before the first unread tab or after the last unread tab
activate after closing a tab:
the first tab, the last tab, the left tab, the right tab, the previous tab or the source tab