问题：Label和网格自动高度和宽度调整的原因以及解决方法

在WPF中，Label不支持TextWrapping属性，因此需要指定TextWrapping属性以实现文本自动换行的效果。

解决方法有两个选项：

1. 将Label替换为TextBlock，并在TextBlock中指定TextWrapping属性。

示例代码如下：

  Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.

2. 在Label中嵌套一个TextBlock，并在TextBlock中指定TextWrapping属性。

示例代码如下：

  
    Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
  

此外，对于初次尝试WPF的开发者，建议阅读更多关于布局指南的书籍或源代码。

另外，需要注意的是，虽然Grid可以实现几乎所有其他布局控件可以实现的功能，但并不意味着应该在任何地方都使用Grid。因为相对于StackPanel、DockPanel和WrapPanel等其他布局控件，Grid的性能开销更大。

此外，WPF中的Label与OSX Cocoa或Qt中的Label不同，它比TextBlock更昂贵。需要仔细阅读有关Label和TextBlock的区别，并评估是否真的需要在此处使用Label。

另外，建议使用Snoop工具来诊断布局问题，该工具提供了快速帮助视频。

同时，可以查看一些使用WPF的开源聊天应用程序示例，以了解作者在应用程序的不同部分选择哪些控件的原因。这样可以更好地理解布局问题。最后，欢迎来到WPF的世界！这是一个很棒的地方！