ArgumentException: 指定的 Visual 已经是另一个 Visual 的子级或者已经是 CompositionTarget 的根。 --Message: 指定的 Visual 已经是另一个 Visual 的子级或者已经是 CompositionTarget 的根。 StackTrace: 在 System.Windows.Media.VisualCollection.Insert(Int32 index, Visual visual) 在 System.Windows.Controls.UIElementCollection.InsertInternal(Int32 index, UIElement element) 在 DynamicClass.MainWindow.隐藏歌曲列表Popup() 在 System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) 在 System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) 在 System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) 在 System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args) 在 System.Windows.ReverseInheritProperty.FirePropertyChangeInAncestry(DependencyObject element, Boolean oldValue, DeferredElementTreeState treeState, Action`2 originChangedAction) 在 System.Windows.ReverseInheritProperty.FirePropertyChangeInAncestry(DependencyObject element, Boolean oldValue, DeferredElementTreeState treeState, Action`2 originChangedAction) 在 System.Windows.ReverseInheritProperty.FirePropertyChangeInAncestry(DependencyObject element, Boolean oldValue, DeferredElementTreeState treeState, Action`2 originChangedAction) 在 System.Windows.ReverseInheritProperty.FirePropertyChangeInAncestry(DependencyObject element, Boolean oldValue, DeferredElementTreeState treeState, Action`2 originChangedAction) 在 System.Windows.ReverseInheritProperty.FirePropertyChangeInAncestry(DependencyObject element, Boolean oldValue, DeferredElementTreeState treeState, Action`2 originChangedAction) 在 System.Windows.ReverseInheritProperty.FirePropertyChangeInAncestry(DependencyObject element, Boolean oldValue, DeferredElementTreeState treeState, Action`2 originChangedAction) 在 System.Windows.ReverseInheritProperty.FirePropertyChangeInAncestry(DependencyObject element, Boolean oldValue, DeferredElementTreeState treeState, Action`2 originChangedAction) 在 System.Windows.ReverseInheritProperty.FirePropertyChangeInAncestry(DependencyObject element, Boolean oldValue, DeferredElementTreeState treeState, Action`2 originChangedAction) 在 System.Windows.ReverseInheritProperty.OnOriginValueChanged(DependencyObject oldOrigin, DependencyObject newOrigin, IList`1 otherOrigins, DeferredElementTreeState& oldTreeState, Action`2 originChangedAction) 在 System.Windows.Input.MouseDevice.ChangeMouseOver(IInputElement mouseOver, Int32 timestamp) 在 System.Windows.Input.MouseDevice.PreNotifyInput(Object sender, NotifyInputEventArgs e) 在 System.Windows.Input.InputManager.ProcessStagingArea() 在 System.Windows.Input.InputManager.ProcessInput(InputEventArgs input) 在 System.Windows.Input.MouseDevice.Synchronize() 在 System.Windows.Input.InputManager.HitTestInvalidatedAsyncCallback(Object arg) 在 System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) 在 System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)