fix MrEd Windows handle-block problem (PR 10183)

svn: r14467

src/mred/mredmsw.cxx

@@ -931,6 +931,8 @@ void MrEdMSWSleep(float secs, void *fds)
       if (rps[result])
         ReleaseSemaphore(handles[result], 1, NULL);
     }
+
+    scheme_collapse_win_fd(fds); /* cleans up */
   } else if (wxTheApp->keep_going) {
     MsgWaitForMultipleObjects(0, NULL, FALSE,
 			      secs ? msecs : INFINITE,