private void paintScreen()
	  // use active rendering to put the buffered image on-screen
	  { 
	    Graphics g;
	    try {
	      g = this.getGraphics();
	      if ((g != null) && (dbImage != null))
	        g.drawImage(dbImage, 0, 0, null);
	      // Sync the display on some systems.
	      // (on Linux, this fixes event queue problems)
	      Toolkit.getDefaultToolkit().sync();
	      g.dispose();
	    }
	    catch (Exception e)
	    { System.out.println("Graphics context error: " + e);  }
	  } // end of paintScreen()