Comment 7 for bug 182930

A) Does the grow/shrink parameter in the tool controls bar not do what you need? It seems like that's what you're looking for it to do (which it already does).

B) The tool actually works visually rather than mathematically right now. So, if you fill in an area and are zoomed out, it is more likely that you will get small gaps. However, if you zoom in and fill an area, it will do it at a "higher resolution".