<Alt-space> doesn't bring up the system menu.
I'm using Windows XP SP2. <Alt-space> normally brings up a system menu (e.g. <alt-space, n> would miNimize the window). On an earlier rxvt version (sorry, don't know which), <alt, space> would work, though <alt-space> didn't. Now neither works.
I appear to be on 2.7.10, from a recent cygwin install.