// The script draws all the ROI Manager
// ROIs in red on the active image.

   manager = RoiManager.getInstance();
   if (manager==null)
      IJ.error("ROI Manager is not open");
   rois = manager.getRoisAsArray();
   img = IJ.getImage();
   ip = img.getProcessor();
   for (i=0; i<rois.length; i++) {
       ip.setColor(Color.red);
       rois[i].drawPixels(ip);
   }
   img.updateAndDraw();