Use the /window command's ability to use a defined Popup menu:

Code:
alias GUI { 
  window -pkodCfB +b @GUI -1 -1 400 400 @MyPopup
  if ($hget(@GUI)) { hfree @GUI }
  hmake @GUI
  hadd @GUI name @GUI
}
menu @MyPopup {
  sclick: {
    if ($active == $hget(@GUI,name)) {
      window -c $active
    }
  }
}

Something like that perhaps.. although the point of the hash table at this point is.. well, there isn't a point.