Thumbnail Zoom Plus is a Firefox plug-in which shows a full-size image pop-up when you hover over a thumbnail or image link. When you hover your mouse over a thumbnail or an image or video link, the add-on displays the full-size image or video still-frame in a floating window. Supported sites include Amazon, Bing, Facebook, Flickr, Google, IMDb, LinkedIn, Netflix, Pinterest, Reddit, Tumblr, Twitter, Yandex.ru, YouTube, Wikipedia, WordPress, Yahoo Images, and many more.
When hovering over the "Open photo viewer" arrows on the top right it shows the first image below the post, and not the original image (the same happens when hovering over the image in the news feed).
On a couple of Facebook posts, the hover images doesn't show the correct picture. Most of the time it works though, which makes it so irritating.
Example post: https://www.facebook.com/tyrionfans/photos/a.546670775405649.1073741828.546601852079208/940543642685025/?type=1
When hovering over the "Open photo viewer" arrows on the top right it shows the first image below the post, and not the original image (the same happens when hovering over the image in the news feed).