Prevent bleeding when Gaussian blurring a selection?

[KevKiev]

Well, I think I screwed up somewhere along the line as when I pasted as new layer in place the selection went white (very odd 'cuz it worked fine on a trial run just messin' about). But, in any event, I simply edited the selection on a separate layer with the alpha locked, gaussian blurred the heck out of it, then merged it back into the normal map. I think that made things about as close to perfect as possible, since even proper Gimp techniques can't overcome the limitations of a game engine. But, yeah, that alpha lock tip was the key. Thanks very much!