怎么用VB.NET做一个记事本

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

OpenFileDialog1.ShowDialog()

RichTextBox1.LoadFile(Me.OpenFileDialog1.FileName, RichTextBoxStreamType.PlainText)

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim fname As String
Me.SaveFileDialog1.ShowDialog()
fname = Me.SaveFileDialog1.FileName

If (fname <> "") Then

If (Me.OpenFileDialog1.FilterIndex = 1) Then
Me.RichTextBox1.SaveFile(fname, RichTextBoxStreamType.PlainText)
Else
Me.RichTextBox1.SaveFile(fname, RichTextBoxStreamType.RichText)

End If

End If

End Sub

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4