Comment 3 for bug 137239

I think the trouble is that Metacity is not tunable enough to do this by design: Metacity is supposed to be a small, simple window manager without a whole lot of options and bells and whistles. Of course we could patch it at the Ubuntu level to behave differently, or to be more tunable, and we could consider some kind of standard about how basic and very common actions work (although I'm not sure that "middle click on maximise button" counts as basic and very common) at, say, the freedesktop level, although currently that role is mostly filled quite reasonably by consensus. If you've found a place where that consensus falls down, such as here, I think it's not unreasonable to ask Metacity or Compiz to change their default behaviour when you middle-click the maximise button as a specific bug (at least at the Ubuntu level; since this has quite recently been the subject of a slightly heated discussion upstream, I doubt the upstream maintainers would upset the boat by changing the behaviour again now.)