I have a problem using copy() in OPENGL:

I'm trying to store a detail of a large bitmap in a small PImage. The example code below works as expected in P3D rendering mode, but with OPENGL the copy() function seems to work only once - in subsequent frames, copy() does not have any effect on what's drawn to the display window.

Is this a bug or is there a way to refresh the bitmap that's drawn to the screen? Your advice would be appreciated.

(I'm using 0090 on OS X 10.3.9)

Code:

import processing.opengl.*;

PImage detail, img;

void setup() {
  size(200, 200, OPENGL); //works fine with P3D
  detail = new PImage(200, 200); 
  img = loadImage("img.jpg");
}

void draw() {
  int startX = round((random(img.width - detail.width)));
  int startY = round((random(img.height - detail.height)));
  
  detail.copy(img, 
		  startX, startY, detail.width, detail.height, 
		  0, 0, detail.width, detail.height);
		  
  image(detail, 0, 0);
}