To bring this thread to an end : as compiz has no official maintainer, it will be soon removed from portage. Sadly, desktop-effects overlay has only 0.9.2 (compiling issues), latest available (non official) ebuilds are for 0.9.4 (cscm is borked) . . . Compiling from source bring too many issues regarding dependencies. So I finally removed compiz, defined xinerama USE flag & recompiled world. Everything is working fine : wine go fullscreen now but gnome 2.32 do not handle dual displayvery well :S I'll have to see if gnome 3 do a better job with dual display and if mutter can do the trick.
