I installed WindowMaker 0.19.2-1 from slink and tried to change the modifier key to Meta instead of Alt.
Both xkeycaps and xmodmap say my Meta key is mod4, where my Alt key is mod1; WPrefs also captures my meta-?? keypresses as mod4-??, ok. I changed all occurences of mod1 with mod4 in ~/GNUstep/Defaults/WindowMaker and it isn't working (neither Alt-?? nor Meta-?? nor any other modifier perform any action); i change it back to mod1 and everything works perfectly (except commandline completion in Midnight Commander, of course :-| ) Afterstep was handling Meta perfectly, so it seems to be something specific to WindowMaker... Ciao! Enrico