>I can't pass judgement on that - because I don't know about the particular problem.
>this can be useful for example if any old data is read-only, but records added in the current session should be editable

Well, you're right that it's hard to pass judgement without knowing full details of a scenario...but editing in grids is not generally a great thing to begin with, and this seems to conjure up a picture to me of a confusing & non-standard interface...