Hi, I've made a simple hack (based on the xmonad one) to get Java applications (which use the XToolkit/XAWT backend) working. With this patch you won't get any grey windows anymore.
The patch for dwm-4.9 is available here: http://files.luizribeiro.org/dwm/dwm-4.9-java.diff Enjoy :-) -- Luiz Ribeiro http://luizribeiro.org/