当 TransitioningContentControl 放在 TabControl 初始选中的 TabItem 中时，它不会重新播放其过渡动画

Describe the bug

当 TransitioningContentControl 放在 TabControl 的第一个 TabItem（索引0）中时，从其他 Tab 切回来不会触发过渡动画
非首个 TabItem（索引>=1）中的 TransitioningContentControl 动画正常

Steps to reproduce the bug

<TabControl> <TabItem Header="Tab 1"> <hc:TransitioningContentControl TransitionMode="Right2LeftWithFade"> <TextBlock Text="Page 1"/> </hc:TransitioningContentControl> </TabItem> <TabItem Header="Tab 2"> <hc:TransitioningContentControl TransitionMode="Right2LeftWithFade"> <TextBlock Text="Page 2"/> </hc:TransitioningContentControl> </TabItem> </TabControl>
1.从Item1（默认选中）切回到tem2，
2.再从Item2切回Item1

Expected behavior

每次 TabItem被选中时都应该播放过渡动画，包括最初选IsSelected的TabItem。
稳定的解决方案：在索引0位置添加一个隐藏的空白 TabItem 占位，让实际内容从索引1开始，如
<TabItem Visibility="Hidden" Width="0"> <hc:TransitioningContentControl TransitionMode="Right2LeftWithFade" /> </TabItem>

Screenshots

https://github.com/user-attachments/assets/3047a36f-2f84-4acf-8d46-7a9ef073f428

NuGet package version

HandyControl 3.5.1

IDE

Visual Studio 2022-preview

Framework type

.Net 8.0

Windows version

Windows 11 (22000)

Additional context

No response

Start by locating the TransitioningContentControl implementation and how it responds to TabControl or TabItem selection changes. Reproduce the provided two-tab example on .NET 8 and compare the first and second TabItems; done means the transition animation plays every time either TabItem is selected, including index 0.