Migrating a Vaadin application to GAE

I'm trying to migrate my existing application to GAE using this tutorial:

http://vaadin.com/wiki/-/wiki/Main/Google%20AppEngine%20HOWTO

When trying to set the application ID, I get following error message:

Cannot set application ID (appengine-web.xml is missing)

I suppose that the reason for this is that I have to set the deployment mode of the Vaadin app to "GAE".

But how can I do this for an EXISTING (not new) project?

UPD 21.08.2011, 20:14 CET:

My WAR directory (it contains appengine-web.xml):

The error I get 开发者_高级运维when trying to deploy the app to GAE.

Eclipse searches for the files in "target/war" (wrong) instead of "war" (correct).

How can I fix this?