With this we always roundtrip position change to the webbrowser.
This avoids conflicts when things change from both directions (app and user).
Also, we fake configure evens when there is no web client to ensure
apps get the events.
This (shouldn't) change any behaviour, but it moves the
webserver parts to a separate file, making the broadway display file
smaller and preparing for later separating out the server to its own
process.
