msdn上的代码，有疑问
If Me.BackgroundImageLayout = ImageLayout.Stretch Then
Me.BackgroundImageLayout = ImageLayout.Center
Else
Me.BackgroundImageLayout = ImageLayout.Stretch
End If

为什么if后面跟的是赋值。。。。
而且根据msdn上的介绍，最后不能完成他所描述的功能

[解决办法]

VB.NET code

Public Class Form1    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load        Me.BackgroundImage = Image.FromFile("c:\1.jpg")'加载一张图片，路径自己设置    End Sub    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click'单击观查结果        If Me.BackgroundImageLayout = ImageLayout.Stretch Then            Me.BackgroundImageLayout = ImageLayout.Center'显示在中央        Else            Me.BackgroundImageLayout = ImageLayout.Stretch'拉伸满背景(form背景）        End If    End SubEnd Class