Recently a patch has been released which will update your current 0.9.8 installations. The small update fixes a bug and includes some new features.
It allows you to quit without problems, there's a new real world time option, and perhaps the biggest new thing is an option to run TerraSync in the background. TerraSync downloads scenery for you as needed as you fly so it is ready next time you launch FlightGear.
You can also now disable fullscreen mode.
Some links have been added to the web page, including a link to the patches. Enjoy!