<br />
<b>Warning</b>:  session_start(): open(/var/lib/php/sessions/sess_eje7v9guajb1s7b9k8sq64ie13, O_RDWR) failed: No space left on device (28) in <b>/var/www/tb-usercake/models/config.php</b> on line <b>51</b><br />
<br />
<b>Warning</b>:  session_start(): Failed to read session data: files (path: /var/lib/php/sessions) in <b>/var/www/tb-usercake/models/config.php</b> on line <b>51</b><br />
!7

static ScreenLens lens;
static RGBImage lastImage;
static Rect diffRect;

p-subst {
  lens = new ScreenLens;
  lens.postProcess = func(BufferedImage img) {
    RGBImage rgb = new(img);
    if (lastImage != null) {
      diffRect = or(rectOfDifferentPixels(lastImage, rgb), diffRect);
      drawBox(img, diffRect, Color.red, 0.8f);
    }
    lastImage = rgb;
    ret img;
  };
  lens.start();
}