Creation of ppt with Live edit : don't make "save in nuxeo" proposed immediately when powerpoint opens

When user creates a powerpoint using Live Edit, the "Save in Nuxeo" box is displayed immediately when powerpoint opens, without the user having to click on "Save". He doesn't even have the time to type content.
The message box should be displayed when the user clicks on Save or closes powerpoint, to have a behavior consistent with Word and Excel liveedits.