I am a newbie learning the ropes with Openhab (and Linux :S). Came across the same issue with trying to save files through the visual studio extension.
I managed to fix this after reading through a bunch of posts and using the fix permissions option in the ophenhabian-config.
at the terminal type: sudo openhabian-config (enter root password)
go to option 10 | Apply Improvements
go to option 14 | Fix permissions
then execute