Why does this break the RichTextBox?

[Kasracer]

Note: Yes I know 2 seperate parts of the statusbar display the samething, that's just for testing it, lol

TotalLines = Convert.ToString(txtBoxChild.Lines.LongLength)
        StatusBarChildtotalLines.Text = "Total Lines: " + TotalLines
        StatusBarChildCurrentLine.Text = Convert.ToString(txtBoxChild.Lines.Length)
        If RecentSave = True Then
            RecentSave = False
            mnuChildSave.Enabled = True
        End If

If I put that in the TextChanged event, or KeyPress event for the TextBox, half the TextBox functions STOP working (like undo() and redo())

Why do they stop working? They are read-only functions, I don't see why that would make them not work!

How else am I supposed to update my statusbar when the user changes something?