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CloseReview for Dictionary Switcher by Gustrónico
Rated 4 out of 5 stars
In the "more" page it appears an image with some options, ie: Detect dictionary as I type, Auto-detec locales and Remember dictionary for current site. It took me a couple of days to find them at last:
Right click on the Dictionary Switcher button that you previously added to add-on bar (see MarkaPola comment)
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