Private Sub RichTextBox1_KeyPress(KeyAscii As Integer)
  Dim lPos As Long
 
  With RichTextBox1
    lPos = .SelStart
 
    If lPos > 0 Then
      Select Case KeyAscii
        Case Asc("?")
          If Mid$(.Text, lPos, 1) = "<" Then
            KeyAscii = 0
            .SelStart = lPos - 1
            .SelLength = 2
            .SelColor = vbRed
            .SelText = "<?"
            .SelStart = lPos + 1
            .SelLength = 0
            .SelColor = vbBlack
          End If
 
        Case Asc(">")
          If Mid$(.Text, lPos, 1) = "?" Then
            KeyAscii = 0
            .SelStart = lPos - 1
            .SelLength = 2
            .SelColor = vbRed
            .SelText = "?>"
            .SelStart = lPos + 1
            .SelLength = 0
            .SelColor = vbBlack
          End If
      End Select
    End If
  End With
End Sub