Android Canvas two activities - content drawn on second canvas
<p>I don't know how this is possible, but a canvas from Activity A is appearing on top of my canvas in activity B.  Both activities are always alive (they are in an activity group).  How is it even possible that content from a canvas on one activity could be showing on top of my other activity?</p>

<p>I call this when i'm done with either activity A or B, but it obviously isn't working:</p>

<pre><code>void clearPlayerCanvas()
{
    runOnUiThread(new Runnable(){
        public void run()
        {

            Canvas canvas = null;
            try
            {

                canvas = holder.lockCanvas();

                if (canvas == null)
                {
                    System.out.println("Cannot lock canvas, skipping MJpeg frame");
                    return;
                }


                canvas.drawColor(Color.BLACK);


            } 
            finally 
            {
                if (canvas != null)
                    holder.unlockCanvasAndPost(canvas);


            }
        }
        });
}
</code></pre>

<p>This code simply overwrites (its supposed to) the current canvas with black.  In any case, i shouldn't even be seeing this black canvas in activity b, but I am.  I am also using  SurfaceHolder.</p>
