code: public Matrix4f pick(float x, float y, float width, float height, int[] viewport) {
          return pick(x, y, width, height, viewport, thisOrNew());
      }
docs: Apply a picking transformation to this matrix using the given window coordinates <code>(x, y)</code> as the pick center
  and the given <code>(width, height)</code> as the size of the picking region in window coordinates.
  
  @param x
  the x coordinate of the picking region center in window coordinates
  @param y
  the y coordinate of the picking region center in window coordinates
  @param width
  the width of the picking region in window coordinates
  @param height
  the height of the picking region in window coordinates
  @param viewport
  the viewport described by <code>[x, y, width, height]</code>
  @return a matrix holding the result