         }
     }
 
+    /// System-applied height constraint, used to resize the format bar as necessary.
+    ///
+    fileprivate var heightConstraint: NSLayoutConstraint? = nil
 
     // MARK: - Initializers
 

        updateVisibleItemsForCurrentBounds()
    }


    // MARK: - Styles


            scrollView.leadingAnchor.constraint(equalTo: leadingAnchor),
            scrollView.trailingAnchor.constraint(equalTo: trailingAnchor),
            scrollView.topAnchor.constraint(equalTo: topAnchor),
            scrollView.bottomAnchor.constraint(equalTo: bottomAnchor),
            scrollView.heightAnchor.constraint(equalToConstant: Constants.formatBarHeight)
        ])

        NSLayoutConstraint.activate([
