Req: better filling algorithm

[v1nce]

The current algorithm associated with the filling tool produces weak results.

I know it is fast but what is the point if the filled region got to be reworked ?

Would it be that slow to use boolean cutting of overlapping/intersecting sections ?
find shapes whose bounding rect contains mouse(x,y)
 sort by surface
  if shape doesn't contain XY discard it.
  currentsmallest = shape
  while shapes exist
   if shape bounding rect does not intersect currentsmallest discards it
   if currentsmallest is inside shape the discards this shape.
   compute intersecting regions
    find currentsmallest
  do while

We still can revert to the current algorithm if there are too many regions.