Some folks asked why VS 2008 and VWD Express 2008 do not have "live" spell checking like Expression Web or SharePoint Designer 2007? Designer is shared with Expression Web and hence code must be there, right? Correct. But there are licensing issues. Office spell checker and dicitonaries are not 100% Microsoft products (you can see copyright information in the Office Help | About information). Expression Web is an Office product so it is using Office spell checker engine directly, same way other Office apps do. Visual Studio is not Office product and hence it cannot directly use or ship components Microsoft may not have license for. My add-in uses separately installed Word via public interfaces which is different from direct usage of Office engine or reshipping third party components in a different application.