code: public void setClip(int x, int y, int width, int height) {
  		predraw();
  		
  		if (clip == null) {
  			GL.glEnable(SGL.GL_SCISSOR_TEST);
  			clip = new Rectangle(x, y, width, height);
  		} else {
  			clip.setBounds(x,y,width,height);
  		}
  		
  		GL.glScissor(x, screenHeight - y - height, width, height);
  		postdraw();
  	}
docs: Set the clipping to apply to the drawing. Note that this clipping takes
  no note of the transforms that have been applied to the context and is
  always in absolute screen space coordinates.
  
  @param x
  The x coordinate of the top left corner of the allowed area
  @param y
  The y coordinate of the top left corner of the allowed area
  @param width
  The width of the allowed area
  @param height
  The height of the allowed area