mixing font attributes

[!NoItAll]

So - I have some text in an RTF control. I want the user to be able to highlight text and apply an attribute. The following code is placed into a button called BOLD and seems to work nicely:

     If rtfText.SelectedText.Length > 0 Then
           rtfText.SelectionFont = New Font(rtfText.SelectionFont, FontStyle.Bold)
     End If

The code above will turn the selected text bold. Great!
But then the user selects the Same text and with the following code placed into a button called ITALIC it removes the bold attribute and replaces it with italics.

      If rtfText.SelectedText.Length > 0 Then
          rtfText.SelectionFont = New Font(rtfText.SelectionFont, FontStyle.Italic)
       End If

Since the users actions are separate - I can not know that they want BOLD and ITALIC, so how do I make sure I keep the existing attribute on the selected text (which, by the way could be part bold and part not-bold) and add italic?

Somehow I need to add the italic attribute to the selected text, not simply replace all attributes with italic.

[!NoItAll]

Ok SOME progress, but not there yet....

Here's new code:

For Bold

If rtfText.SelectedText.Length > 0 Then
           rtfText.SelectionFont = New Font(rtfText.SelectionFont, FontStyle.Bold Or rtfText.SelectionFont.Style)
End If

For Italic

If rtfText.SelectedText.Length > 0 Then
           rtfText.SelectionFont = New Font(rtfText.SelectionFont, FontStyle.Italic Or rtfText.SelectionFont.Style)
End If

Notice that I added the OR, and apply the new font style to the current. This works well, but only when the second selection is of text with all the same attribute.
If I select a section of text and make it bold, then select a portion of the bold text along with a portion of the normal text then the above italic code will make everything just italic - removing the bold

Please don't tell me I have to go character by character - that would suck!
Granted - somebody has to, but I would prefer it be the lower level routine...