 class VCreate:View, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout
 {
     private(set) weak var collectionView:VCollection!
+    private weak var layoutBarTop:NSLayoutConstraint!
     private let kBarHeight:CGFloat = 64
     private let kCollectionBottom:CGFloat = 40
     

        addSubview(collectionView)
        addSubview(viewBar)
        
        NSLayoutConstraint.topToTop(
            view:viewBar,
            toView:self)
        NSLayoutConstraint.height(

    }
    
    //MARK: collectionView delegate
    
    func scrollViewDidScroll(_ scrollView:UIScrollView)
    {
        let offsetY:CGFloat = scrollView.contentOffset.y
        let usableOffset:CGFloat
        
        if offsetY < 0
        {
            usableOffset = 0
        }
        else
        {
            usableOffset = -offsetY
        }
        
        layoutBarTop.constant = usableOffset
    }
    
    func collectionView(_ collectionView:UICollectionView, layout collectionViewLayout:UICollectionViewLayout, sizeForItemAt indexPath:IndexPath) -> CGSize
    {
