netbeans: add reference to project

Hi there,
I have a several projects in netbeans I’m working on simultaneously - one is the “Vaadin application” and a several “java class library” projects. I need my Vaadin app to use the classes from a “class library project”. Is it possible for Vaadin app to have a reference to another project (not the jar file)? If I want to add a reference from one regular java project to another, all I need to do is to right-click on “libraries” and select “add project…”
Maybe there are some restrictions of which I wasn’t aware of? maybe it’s a netbeans issue?