Private Const EM_GETLINECOUNT As Integer = &HBA
    Private Const EM_GETLINE As Integer = &HC4
    Private Const EM_LINELENGTH As Integer = &HC1
    Private Const EM_LINEINDEX As Integer = &HBB
 
    Private Declare Function SendMessageINT Lib "user32.dll" _
        Alias "SendMessageA" (ByVal hWnd As IntPtr, _
        ByVal wMsg As Integer, ByVal wParam As Integer, _
        ByVal lParam As IntPtr) As Integer

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim LineCount As Integer = SendMessageINT(TextBox1.Handle, EM_GETLINECOUNT, 0, IntPtr.Zero)
        Dim counter As Integer = 0
        Dim LineIndex As Integer = 0
        Dim lineLength As Integer
        Dim curLine As String = ""
        Dim stringPTR As IntPtr
 
        For counter = 1 To LineCount - 1
            'Get Index for line we want to retrieve
            LineIndex = SendMessageINT(TextBox1.Handle, EM_LINEINDEX, counter, IntPtr.Zero)
            'GetLineLength
            lineLength = SendMessageINT(TextBox1.Handle, EM_LINELENGTH, LineIndex, IntPtr.Zero)
            'Create the buffer
            curLine = New String("0"c, lineLength + 2)
            Mid(curLine, 1, 1) = Chr(lineLength And &HFF)
            Mid(curLine, 2, 1) = Chr(lineLength \ &H100)
            'Get the pointer for a buffer
            stringPTR = System.Runtime.InteropServices.Marshal.StringToHGlobalAnsi(curLine)
            'Fill the pointer with the current line
            SendMessageINT(TextBox1.Handle, EM_GETLINE, counter, stringPTR)
            'Read the line
            curLine = System.Runtime.InteropServices.Marshal.PtrToStringAnsi(stringPTR)
            curLine = curLine.Substring(0, lineLength)
            'fill textbox2
            TextBox2.Text = TextBox2.Text + curLine + vbCrLf
            'clear out the space
            System.Runtime.InteropServices.Marshal.FreeHGlobal(stringPTR)
            stringPTR = IntPtr.Zero
        Next
 
    End Sub