R files with no commit button cannot be saved

[mslegrand]

R files with no commit button cannot be saved

This issue arises because a file is flagged as modified only after a change has been committed.
Consequently, any changed to an app.R, or any *.js cannot be detected because of a lack of commit button.
To solve this we can either introduce more buttons (yuk) or notify the server when ever a notSaved status changes. A notSaved status would be sent whenever the value of undoStack.length>0 changes.