By "FX" are you referring to Firefox? Or something else? If it's Firefox, is the compressed file named firefox-23.0.tar.bz2 (or something similar, depending on version)? If so, I just downloaded it and extracted its contents. There's nothing to install. Simply extract its contents where you want Firefox installed--on my computers, that would be /usr/local/firefox, and that's it. Then you can just run the executable file named firefox. I didn't actually check, but it's probably the same with Thunderbird. For readers in general who may not know this, I'll be a little more specific. You extract the compressed file wherever you want, and if that's not the location you ultimately want the files installed, you can move the entire subdirectory it created to where you want. For example, I download everything into /data/downloads; when I uncompressed the file it created a subdirectory named firefox there, i.e., /data/downloads/firefox. To install it in /usr/local, just move the firefox subdirectory over there, i.e., /usr/local/firefox. Fire up Synaptic and 'search' for desktop environment and/or specific names, such as kde, xfce, lxde, etc. Install any or all of them. Be sure to grab additional goodies for whichever you're installing, such as kde-icons-crystal or xfce4-artwork (but you can always come back for more later). Apply your choices, then log out. When you're on the login screen, you'll now have choices besides Unity (yay! I don't like Unity at all!) in a drop-down menu...I can't think of how to explain where it is, but you'll find it. FIRST make your selection, then log in. Try out the different DEs you installed and see which, if any, you like. (I'm KDE all the way, but occasionally log in with others just for the fun it.) You can uninstall anything you don't like.