Visual Basic

Private Sub TextBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyDown
    If e.KeyCode = Keys.Enter Then
        MsgBox(TextBox1.Text)

    End If
End Sub

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
       {
           if (e.KeyChar == (char)(0x0D))
               MessageBox.Show("Enter Pressed");

       }

Private Sub txtTest_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtTest.KeyDown

        If e.KeyCode = Keys.Enter Then
            MsgBox("You pressed the Enter Key")
        End If

    End Sub

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

    Dim response As MsgBoxResult = MsgBox("the prompt", MsgBoxStyle.MsgBoxHelp + MsgBoxStyle.Information + MsgBoxStyle.YesNo, "The Title")

    MsgBox(response)

End Sub

Private Sub FormMain_HelpRequested(ByVal sender As Object, ByVal hlpevent As System.Windows.Forms.HelpEventArgs) Handles Me.HelpRequested
    MsgBox("help Requested")
End Sub

    Private helpTopic as integer =0

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

        helpTopic = 1
        Dim response As MsgBoxResult = MsgBox("the prompt", MsgBoxStyle.MsgBoxHelp + MsgBoxStyle.Information + MsgBoxStyle.YesNo, "The Title")

        If response = vbYes Then
            'User Selects Yes
        Else
            'Do something else if anything
        End If

    End Sub

    Private Sub FormMain_HelpRequested(ByVal sender As Object, ByVal hlpevent As System.Windows.Forms.HelpEventArgs) Handles Me.HelpRequested

        Select Case helpTopic
            Case 1
                'User want help with topic 1

            Case Else
                'User called help for something else

        End Select
    End Sub

Private Sub Button3_Click(...)
  AddHandler Me.HelpRequested, AddressOf Me.MsgBoxHelpRequested

  Select Case MessageBox.Show("Text","Title", MessageBoxButtons.YesNoCancel, _
                              MessageBoxIcon.Question, MessageBoxDefaultButton.Button2, 0, True)

  End Select
End Sub

Private Sub MsgBoxHelpRequested(...)
   MessageBox.Show("got here")
End Sub