Change J2EE version of NetBeans Project

A java project I've been working was initially started as J2EE1.4 one, but finally had to be moved to J2EE5. Apparently, there's no GUI way to do this in NetBeans (nor 6 neither 5.5).

When you select Project->Properties->Run, J2EE version is just displayed in a text field which value I couldn't change. Maybe this is a bug of NetBeans, maybe this is an intentional limitation.

Anyway, after some painful hours spent in moving classes and configs into a newly created J2EE5 project and fighting errors popped, I just took an advice of a fellow developer, checked how things are done in project.properties file and put j2ee.version=1.5 instead of 1.4.