TL;DR: Hell yeah, thank you so much for this addon!

Several years ago I had an addon which also reopened the last opened tab, when closing, but at some point it wasn't compatible anymore. Think it was the google toolbar. You get so addicted by such a minor functionality, but only if you experience it. Like the red pill of the matrix. Often tried to write it myself, but some weird behaviour robbed my motivation, dunno. Thanks!