I'm using Firefox Nightly version 61.0a1 (2018-05-07) on a Mac running High Sierra. When I want to UPLOAD a jpg file to a website the preview in the Finder does not show; I get a generic file icon and the letters "jpg" in the center. There is no content type "jpg" or "jpge" available in the browser Preferences/Applications and there does not seem to be a means to add this content type. I would like to see the preview saved by Photoshop prior to uploading as a last check that I'm sending the correct file. If I use Nightly to open a file and select a jpg file-type, the preview shows. The specific website is one I use for ordering products. It still requires Flash to run correctly: trade.4over.com Any help you have is appreciated.