Emmanuel:

"My" Autosave would be located in Preferences with a check-box to turn it on/off, and a field or drop-down box to set the interval.

In OpenOffice the Autosave works after a specified interval, regardless of what you are doing. If the file is large, you notice a short delay because everything is blocked during saving.

If I were you, I would start with a very simple feature, and if necessary refine it.

Hans