Recently ,I encounter a problem that how to convert mindmanager to freemind in Ubuntu .By searching in internet,I find a effective method to solve this problem,using python script below .
http://www.liberatedcomputing.net/mm2fm/scripts/mm2fm
Maybe you have not install libxslt module in your computer ,so you should install it firstly.
sudo apt-get install python-libxslt1
Then,
chmod +x mm2fm
This script syntax is
mm2fm FILENAME
It is simple to use.