After an attempt at hacking “window packing” into Jendela I ran into a bit of a showstopper: Metacity doesn’t support _NET_MOVERESIZE_WINDOW. Now this is a bit of a problem, because “window packing” is all about moving windows around on the screen.
Confusingly Metacity does register the relevant XAtom, meaning that wmctrl doesn’t work (it’ll first try the XAtom, if it exists it uses the EWMH way, otherwise it reverts back to calling XMoveResizeWindow). Bad, bad Metacity!
Well, it turns out the code is already in Metacity, just commented out. The changelog says it’s pending “feature thaw”, whatever that means. Apparently something’s frozen solid because it’s been pending since July 2004
I decided I need to take a stab at this and raised bug 344521.