Public Sub CreateMyMultilineTextBox()
    ' Create an instance of a TextBox control.
    Dim textBox1 As New TextBox()
    
    ' Set the Multiline property to true.
    textBox1.Multiline = True
    ' Add vertical scroll bars to the TextBox control.
    textBox1.ScrollBars = ScrollBars.Vertical
    ' Allow the TAB key to be entered in the TextBox control.
    textBox1.AcceptsReturn = True
    ' Allow the TAB key to be entered in the TextBox control.
    textBox1.AcceptsTab = True
    ' Set WordWrap to true to allow text to wrap to the next line.
    textBox1.WordWrap = True
    ' Set the default text of the control.
    textBox1.Text = "Welcome!"
End Sub

imports System
imports System.Drawing
imports System.Windows.Forms

public class TextBoxTextChanged : inherits Form

  dim txt as TextBox
  dim btn as Button
  dim strOriginal as string

  public sub New()
        Text = "TextBox Modified and TextChanged"
    Size = new Size(300, 375)

    txt = new TextBox()
    txt.Parent = me
    txt.Text = "Enter text here."
    txt.Size = new Size(280, 275)
    txt.Location = new Point(10,10)
    AddHandler txt.TextChanged, AddressOf txt_TextChanged
    txt.Multiline = true
    txt.BorderStyle = BorderStyle.Fixed3D
    txt.ScrollBars = ScrollBars.Vertical
    txt.Anchor = AnchorStyles.Left or AnchorStyles.Right or AnchorStyles.Top or AnchorStyles.Bottom
    strOriginal = txt.Text

    btn = new Button()
    btn.Parent = me
    btn.Text = "Check "
    btn.Location = new Point(20,320)
    AddHandler btn.Click, AddressOf btn_Click
    btn.Anchor = AnchorStyles.Bottom

  end sub

  public shared sub Main() 
    Application.Run(new TextBoxTextChanged())
  end sub

  private sub txt_TextChanged(ByVal sender as object,ByVal e as EventArgs)
    Console.WriteLine("txt_TextChanged")
    if strOriginal = txt.Text then
      txt.Modified = false
    else
      txt.Modified = true
    end if
  end sub

  private sub btn_Click(ByVal sender as object,ByVal e as EventArgs)
    if txt.Modified then
      Console.WriteLine("modified.")
      strOriginal = txt.Text
      txt.Modified = false
    else
      Console.WriteLine("not been modified." )
    end if
  end sub
end class