Just write a quick macro for Visual Studio that would replace < with < and > with >, etc. I am probably the 1000th person to do that. Yet, it proved to be surprisingly hard.

• DTE.ActiveDocument.Selection is an Object. No methods, no nothing. Need to cast to TextSelection to do anything useful with it.
• TextSelection.ReplacePattern() happily replaces one pattern, then loses selection. Attempts to artificially restore selection failed, as TopPoint and BottomPoint properties are read only. MoveToPoint() did not do the trick either. I am still not sure how to tell the IDE to select the text from here to there.
• If you attempt to do something like Selection.Text = Selection.Text.Replace((...) it works fine for one line, but for multiline selection it inserts lots of spaces and generally looks very weird. It also takes a lot of time and occasionally throws exceptions. A non starter.
• Tried to use DTE.Find object, could not find a way to close programmatically the damn Find window. Fortunately DTE.Find.FindReplace() works without opening the window.

Oh yeah, if you try Googling for it – forget about it. You are drowning in crap. Bing is slightly better, but still no help there.

Final solution:

    Sub EscapeXmlChars()
        Replace("&", "&")
        Replace("<", "&lt;")
        Replace(">", "&gt;")
    End Sub

    Sub UnescapeXmlChars()
        Replace("&lt;", "<")
        Replace("&gt;", ">")
        Replace("&amp;", "&")
    End Sub

    Private Sub Replace(ByVal find As String, ByVal replace As String)
        DTE.ActiveDocument.Activate()
        DTE.Find.FindReplace( _
        vsFindAction.vsFindActionReplaceAll, _
        find, _
        vsFindOptions.vsFindOptionsMatchInHiddenText, _
        replace, _
        vsFindTarget.vsFindTargetCurrentDocumentSelection)
    End Sub

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