Add undo/redo functionality.

[Bert Timmerman]

Your data is sacred.
It's that simple, really.
When one ensures that a machine can't lose a user's work, interfaces become a lot simpler; no more dialog boxes asking questions like, "Are you sure you want to delete that entry?"; no more remembering to click a "Save" button like it's a nervous twitch.
You never need to regret any action you take, because any action you take can instantly be undone.
Not to mention your complete lack of terror when you're in the middle of working on your computer and the power goes out.

Source: http://www.humanized.com/about/

[Bert Timmerman (bert-timmerman)]

Maybe create a (temporary) session file for storing all actions/changes on parameters/values until the "save" button is pressed, and finally a fpw file is created.
After the data is stored in the fpw file, free the memory containing the information and reset the (temporary) session file.