I reworked the default Bleachbit icon in Gimp and gave it a "Matrix" look that works well with light or dark backgrounds and I think looks good too. To replace the default Bleachbit icon with the improved version, just replace the image files "bleachbit.png" and "bleachbit.xpm" with their respective replacement versions from the unpacked file. The default Bleachbit images are usually found here: /usr/share/pixmaps.