Private Sub RichTextBox1_KeyDown(sender As Object, e As KeyEventArgs) Handles RichTextBox1.KeyDown
If e.KeyCode = Keys.Add AndAlso e.Modifiers = Keys.Control Then
'increase the font size
ElseIf e.KeyCode = Keys.Subtract AndAlso e.Modifiers = Keys.Control Then
'decrease the font size
End If
End Sub