The last two lines of my .xinitrc looks like this
xterm -g 80x24+10+10 -bg black -fg green &
metacity
When I used twm, I could exit it from the menu (return to the tty where I run xinit), but how do you exit metacity? The man metacity does not mention this, but it refers to the panel menu (which I don't have). Maybe it's there?