flood erase in Paint tool

Hi,

I wonder if there is an easier way to paint shapes with holes in them by 
methods other than by erasing pixels at a time? For instance, a nut can 
be drawn by putting a small circle in a larger hexagon and flooding it 
(the circle) with "transparent" paint.

Is it possible to "unfill flood" (i.e. flood an area with 100% 
transparency) with the Paint tool in Squeak?

Thanks in advance. I really like the way you folks respond quickly and 
precisely to newbie queries.

Subbu