@steve
As far as I know, Alex knows it (it was also in one of the last LingQ newsletters).
The bookmarklet is explained in detail here: Do You Know You Can Change Your Dictionary Settings In Li...
and here (in German): http://bit.ly/gB9IYI
Some French-German Bookmarklets (can be used as examples) are provided here: http://bit.ly/esoL7A
When I open the LingQ provided external dictionaries, the popup window (if open) closes, opens and also changes its position (in Chrome). That is annoying.