Greasy Fork is available in English.
Show direct links to download biggest Flickr image available and some other sizes.
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I don't met your issue. Maybe it conflict with other script/addon you use.
Please tell me the steps to reproduce this bug.
5.0.2 bug
The newest version is going crazy for me, putting multiple copies of the checkbox options on the photo page on it every few seconds. Latest shipping firefox and updated greasemonkey.