public void noCursor() {
    if (!cursorVisible) return;  // don't hide if already hidden.

    if (invisibleCursor == null) {
      invisibleCursor = new PImage(16, 16, ARGB);
    }
    // was formerly 16x16, but the 0x0 was added by jdf as a fix
    // for macosx, which wasn't honoring the invisible cursor
    cursor(invisibleCursor, 8, 8);
    cursorVisible = false;
  }