setLabel method
Implementation
void setLabel( int index, String? label, bool moveFlag ){
if( moveFlag ){
_obj.move( index );
}
if( _label[index] != null ){
if( _index[_label[index]] == index ){
_index.remove( _label[index] );
}
_label[index] = null;
}
if( label != null ){
if( label.isNotEmpty ){
_label[index] = label;
_index[label] = index;
}
}
}