There is no "conversion" really possible here, as the logic behind a web site UI is quite "different" (browser code vs server code, ajax or not, no MODAL pages, as are usually the windows, so no stock of open windows you can simlply close, etc)
So you can easily import all classes and collections of server procedures and reuse that code with quite simple changes, if any, but the UI itself is more easily redone than anything...
you CAN copy and paste UI elements between webdev and windev, but you will have styles problems, as they are not mamaned the same way in both tools.
