How to open to in unknown encoding to edit (tw.pol) in Ubuntu?
When all else fails, use the terminal.
Try asking for some info on the file
$ file tw.pol
Open it in vi (emacs if you must)
$ vim tw.pol
A quick google search tells me that .pol is a file extension used by Microsoft to manage registry keys.
If you cannot open a file with gedit, try the Gnome Hexadecimal Editor, which can be installed at the command line with:
sudo apt-get install ghex2
or search for hex editor in the ubuntu software center.