I reinstalled Aptana Studio today to see if the internal preview issue was fixed somehow. It wasn't. I don't know why, but they simply put it down to bad browser configuration on the host system(s) (in our case, Linuces).

After some reading, I found a solution.

I didn't say 'the solution'. I found a solution. It works for me, and as usual, YMMV.

The trick is not the point the MOZILLA_FIVE_HOME environment variable to /opt/mozilla/bin (or /usr/bin, or wherever your 'firefox' executable is located). On Arch Linux systems, it is /opt/mozilla/lib/firefox-VERSION.

So, without further ado, create aptana.sh in /etc/profile.d, and put the following two lines in there:

export MOZILLA_FIVE_HOME=/opt/mozilla/lib/firefox-2.0.0.11
export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/opt/mozilla/lib/firefox-2.0.0.11"

Make the file executable by issuing chmod +x /etc/profile.d/aptana.sh and you are done. If you need the aptana right now, simply source the file: source /etc/profile.d/aptana.sh. After that, don't close the console, run aptana directly from it. At least under GNOME, whatever env. vars you set in graphical terminal (like gnome-terminal) seem to be lost when you close it. But they will be properly set at next system boot.