Whenever you download any file in your mozilla firefox browser, a new window named downloads appear. You might feel it irritating to switch back and forth to see the progress of your downloads in the new window and the current window of firefox. To solve this problem, a better option would be the downloads tab instead of downloads window for all downloads so that seeing the progress of your downloads and managing your downloads would become easy as you just need to switch to another tab instead of another window.
Mozilla Firefox Extension Addon Downloads
To do this, you need to install mozilla firefox extension addons made for this purpose. Downloads in Tab | Mozilla Add-Ons.