// module has to be visible already
// if img == null, we restore the module's non-transient icon
svoid dm_transientModuleIcon(BufferedImage img) {
  O mod = dm_current_mandatory_generic();
  Container f = dm_frame(mod);
  if (f == null) ret;
  if (img == null) 
    img = loadImage2(or(dm_moduleIcon(), (S) dm_getOS moduleDefaultIconID()));
  setPIFrameIconImage(f, img);
}