Where do Grails / IntelliJ IDEA store .class files?

I just can't find the .class files for my Groovy source code in IntelliJ IDEA Grails projekt. I have created a grails application "qotd" and a plugin "selenium" which you know is a kind of grails application. So just to keep things in order, a screenshot of my Grails View: Grails View

As you can see, I have source code for Java and Groovy. Both have the same package "de.it2m.testcases". Could this be the problem? Anyway, now I need to know where the .class files are stored. I have compiled the "qotd" application and its "selenium" plugin with the "grails run-app" command without errors, so I am pretty sure there must be .class files somewhere. I already found the class file for the SeGridTest.java class at:

... IntelliJ workspace \ qotd \ out \ production \ selenium-inplacePlugin \ de \ it2m \ testcases

Unfortunately there is no "SeleniumTest.class" in this directory (as I expected it to be). I have also looked through the ".grails" directory, but without any success. Where can I hide SeleniumTest.class ...?

Note. I am working on Windows 8.1 Pro, IntelliJ ultimate 13.1.4 and Grails 2.3.8.