Bug 129755 [Decorators] CompositeImageDescriptor: Problem on overlay with transparent areas in PNG
bundles/org.eclipse.jface/src/org/eclipse/jface/resource/CompositeImageDescriptor.java
imageData.setPixel(xx, yy, newPixel);
                        }
                    }
                }
            }
            return;
        }
        int maskPixel = src.transparentPixel;
        for (int y = 0; y < src.height; y++) {
            for (int x = 0; x < src.width; x++) {
                int pixel = src.getPixel(x, y);
                if (maskPixel < 0 || pixel != maskPixel) {
                    int xx = x + ox;
                    int yy = y + oy;
                    if (xx >= 0 && xx < imageData.width && yy >= 0
                            && yy < imageData.height) {
                        int newPixel = map[pixel];
                        if (newPixel < 0) {
                            RGB c = palette.getRGB(pixel);
                            map[pixel] = newPixel = alloc(out, c.red, c.green,
                                    c.blue);
                        }
                        imageData.setPixel(xx, yy, newPixel);
                    }
                }
            }
        }
    }
    /* (non-Javadoc)
     * Method declared on ImageDesciptor.