Very good! Does exactly what it says on the tin. One important feature is missing, though (for which I leave a star off): You should be able to open windows sequentially, either with a fixed user-specified delay between opening each one, or with an option for the add-on to detect when each new window has *finished loading*, and only open the next one when that has occurred (subject to a user-specifed maximum timeout). Or even better, have a setting for "Load a maximum of *n* windows simultaneously". Without these kind of features, opening (say) 300 tabs at once can crash the browser! (Yet you might really want them all open, not "Open when selected", though that's a nice feature as well).