I heavily use firefox on our intranet to open log files. The files are with .log extension and normally firefox, when I click on a file in the URL, use to download the file and let my external file editor to open the file. Suddently from couple of days, firefox started opening the files in a new tab and this is not what I needed, since some of these log files are 100 of megabytes in size and I can not review these logs in firefox window. I did a vast search in google and never able to reset the old behaviour. I have reinstalled firefox and it did not help either.