Rated 5 out of 5 stars
it seems that
doesn't do anything in newest firefox versions.
Actually it does.
If it is enabled, you see a little progress bar inside 'download'-button and it turns into a green arrow, after a download is finished.
If this option is disabled, you won't see any progress bar or green arrow inside 'download'-button. Instead the classic downloads window appears once a download starts.
One "feature" got removed by Moz, because it was too buggy: 'displaying finished downloads inside library'.
I guess thats what you are referring to.