internal virtual void OnVerticalFlowDirectionChanged(VerticalFlowDirection oldValue, VerticalFlowDirection newValue)
 {
     if (oldValue != newValue)
     {
         ArrangePanel();
     }
 }
 internal virtual void OnVerticalFlowDirectionChanged(VerticalFlowDirection oldValue, VerticalFlowDirection newValue)
 {
     if (oldValue != newValue)
     {
         ArrangePanel();
     }
 }