用vb.net做系统登陆框 遇到了问题里面有详细代码

主要想问大家那个公有属性MyUser在代码里起了什么作用 然后具体公有属性是怎么用的

Inherits System.Windows.Forms.Form
'定义一个变量存放是否可以关闭系统登录对话框的标志
Dim blnClose As Boolean
'定义存放用户名的变量
Dim strUserID As String

'为frmPassword类创建一个公有属性MyUser
Public Property MyUser() As String
Get
MyUser = strUserID
End Get
Set(ByVal Value As String)
strUserID = Value
End Set
End Property

Private Sub btnOk_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOk.Click
cmdAuthority.CommandText = "SELECT 用户名 FROM 用户 " & _
"WHERE 用户名 = '" & txtUserID.Text & "'" & _
"AND 密码 = '" & txtPassword.Text & "'"
'打开数据库连接
cnQTGL.Open()

'用输入的用户名和密码在用户表查询记录，将查询结果赋给strUserID
strUserID = CType(cmdAuthority.ExecuteScalar, String)


'如果结果是空串, 说明找不到该用户, 可能是用户名或密码错误

If strUserID = "" Then
MessageBox.Show("用户名或密码错误!", _
"身份确认失败", MessageBoxButtons.OK, _
MessageBoxIcon.Error)
'身份错误不可按OK离开
blnClose = False
Else
'若找到, 可以离开
blnClose = True
strUserID = txtUserID.Text
End If

'关闭数据库连接
cnQTGL.Close()

End Sub

Private Sub btnCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancel.Click
MyUser = ""
blnClose = True
End Sub

Private Sub frmPassword_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
blnClose = True
End Sub

Private Sub frmPassword_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
e.Cancel = Not blnClose
End Sub
End Class
在确定按钮里有用到公有属性 这是起什么作用