public void toggle(JFXDrawer drawer){
  if (!drawers.contains(drawer))   addDrawer(drawer);
  if (drawer.isShown() || drawer.isShowing())   drawer.close();
 else {
    updateDrawerPosition(drawer);
    drawer.open();
  }
}

public void toggle ( JFXDrawer drawer ) { if ( ! drawers . contains ( drawer ) ) addDrawer ( drawer ) ; if ( drawer . isShown ( ) || drawer . isShowing ( ) ) drawer . close ( ) ; else { updateDrawerPosition ( drawer ) ; drawer . open ( ) ; } }
toggle a drawer in the stack
