The removal of the download status bar at the bottom of the browser is a major UI failure and this feature needs to be returned. I spent 30 minutes attempting to download/extract a settings file from an Addon until I noticed that Firefox was silently downloading it to my Downloads folder without any notification that it had started or completed. The download bar was a known solution for this; The bar itself did not obscure the current webpage, provided immediate feedback on download initiation, progress, and completion. Provided quick access to open the file(s) or find options about the file(s), and the download bar could be dismissed quickly if the vertical page space was required/desired. The hidden download tray is a horrible design idea, makes it difficult to see if your downloads have started successfully, when they have completed, and how to access them. Additionally, the introduction of 'hint' popups to support this feature actively obscure the webpage you're viewing, making them dramatically worse than the download bar, which left the page completely usable and only required a few pixels of height at the bottom. This is a major design flaw.