Thanks but this doesn't satisfy my feature request: I want to save each selection as an separate individual jpg, png or whatever. I'm not interesting in saving layers.
To recap: I want to be able to 1) make multiple selections and 2) save each one as an individual separate bitmap jpg/png etc file. Paint.NET allows 1) but it cannot save each selection as a separate individual bitmap file - i.e. a jpg, png etc. Once I have made the selections I want to be able to click a button or menu option, and have Paint.NET ask me, for each selection, what file name to save that selection as, to repeat this until all selections have been saved.