ImageBuffer bufx = g.createBuffer(
(int)b.getWidth()+blurRadius*2,
(int)b.getHeight()+blurRadius*2);
//render shadow to buffer
bufx.clear();
GFX g2 = bufx.getGFX();
g2.setPaint(FlatColor.BLACK);
g2.translate(10, 10);
fillShape(g2);
g2.translate(-10, -10);