How to find package list in katalon studio?

I am looking for a list of all the packages in tree in a small window of katalon studio.
This allows me to see all the functions predefined to its package.
I managed to have it once, but since I can not do it anymore.
can anyone help me?
It looks like an tree like this:

org.codehaus.groovy …

And by clicking on the testcase.jar I can see all the functions that exsite in.

thanks for reading.


For those interested, I found what I looked for. I show you a screenshot. this was called Package Explorer.

But I have another question:
Why is the source not finding?

And when I attach the source, and I restart my test, I always have the same error message, as if the source is not taken into account.

Am I going to have more information about my test errors once the source is properly attached?