The output file list something like AN HALF of the opened urls.
Maybe there is another config file to check?

Firefox 33.0
Ubuntu 14.04.1 LTS

Carlo:

ho provato a usare save_firefox_tabs ma mi da un errore
Alla riga 112 dice
TypeError: 'NoneType' object has no attribute 'getitem'

        try:        # some tabs aren't part of any group
            ext = json.loads(t['extData']['tabview-tab'])
            groupID = ext['groupID']
        except KeyError:
            groupID = 'no group tabs'