Mark -- your #6 and #7 images look to me at least like the MsgBox max width is reached and then the text is wrapped (not a 'true' line feed)
Text wrap occurs on my comp with my screen res when I = 40.
Sub AddMs()
Dim i As Long
Dim s As String
s = String(30, "M")
For i = 31 To 50
s = s & "M"
Call MsgBox(s, vbOKOnly, "Length = " & i)
Next i
End Sub
Msgbox width increased up to I = 39, and then stays that wide with the text wrapping.
If there's a LF embedded, that forces a new line of course but the previous text stays wrapped
Paul