Trying to understand decorators and building screens.

[Robert Wynkoop]

Using a plugin I created as an example.  The main-decorator includes
name=GlobalDecorator component://common/widget/CommonScreens.xml.

In CommonScreens.xml I see:

  <!-- Global decorator for General Screens/Pages -->
    <screen name="GlobalDecorator">
        <section>
            <widgets>
                <include-screen name="GlobalActions" />
                <include-screen name="GlobalDecorator"
location="${groovy:commonScreenLocations.GlobalDecorator?commonScreenLocations.GlobalDecorator:commonDecoratorLocation}"/>
            </widgets>
        </section>
    </screen>

Can someone summarize how
location="${groovy:commonScreenLocations.GlobalDecorator?commonScreenLocations.GlobalDecorator:commonDecoratorLocation}"/>
works?

I'm not sure how to follow the flow into that.  Where is the related
source to the above location?

Robert Wynkoop