             else { return }
         
         isDragging = true
+        
+        assert(previousTranslation == nil)
         
         //horizontalScroller?.alwaysVisible = true
         //verticalScroller?.alwaysVisible = true

                
            case .changed:
                
                let delta = panGestureRecognizer.translation(in: self)
                
                drag(by: delta)
                

            }
        }
    }
    
    // Used for calculating delta
    private var previousTranslation: CGPoint?
    
    private func beginDragging() {
        
