code: public void openMenu(boolean withAnim) {
          mMenuOpen = true;
          openMenuDrawable(mMenuBtnDrawable, withAnim);
          if (mOnMenuClickListener != null) {
              mOnMenuClickListener.onMenuOpened();
          }
      }
docs: Mimics a menu click that opens the menu. Useful for navigation
  drawers when they open as a result of dragging.