You're on a page and you want to download a file, quietly and in the background. But Firefox pops up this large panel to show you the current downloading file and several other files. How do you get rid of this, and keep download simple and non-obtrusive?

1. Browse to about:config
2. Accept warnings
3. Find setting browser.download.alwaysOpenPanel
4. If it was set True, that was the problem. Toggle its setting to False.