For whatever it's worth, the document/view management is undergoing a significant redesign for a future release. The goal is to make it easier to navigate/view the content you care about, and reduce the need for complicated screen layouts.
Actually, you can do this. I went through the same problem you have and I found it quite annoying. Just play around with the different "thumb tacks" for the various windows, and you should be able to create a similar view in EG 4.1 as you had in version 3.
You can set it up like EG 3.0. If you right click next to the "Project Designer" tab (not on it) you will get three options to choose from: Dockable, Hide, and Floating. If you select Dockable you can change the size of the Project Designer screen. If you move the Project Designer screen so it is in the upper half of E.G. horizontally from now on all of your data set results will appear in the grayed out area below the Project Designer screen.