question: public void add ( WXDomObject child , int index ) { if ( child == null || index < - 1 || sDestroy . get ( ) ) { return ; } if ( children == null ) { children = new ArrayList < > ( ) ; } int count = children . size ( ) ; index = index >= count ? - 1 : index ; if ( index == - 1 ) { children . add ( child ) ; super . addChildAt ( child , super . getChildCount ( ) ) ; } else { children . add ( index , child ) ; super . addChildAt ( child , index ) ; } child . parent = this ; }
target:  Add the given WXDomObject as this object's child at specified index.