I’m following a tutorial in 2.8, and I see it’s possible to drag from the corners open new windows and to close them again, but it doesn’t seem to be feature in my install (I’m on Windows 10 Pro 64-bit). I googled about how to do it, and found that I should be able to just drag from the corners, but it’s not working that way for me. When I drag from the corner, as far into the corner as it’s possible to click without getting the scroll bar or something else, all I get is the selection rectangle. I zoomed in on the corners with the magnifier, and I see nothing that would indicate that it’s a place to drag or anything. Is there some option that has to be enabled before this feature works? Or is there anything anyone can suggest? Is there an alternate way to close the windows, a key command or menu item? Thank you for your help!
You can right click on the separating lines between editors, as an alternative. Dragging corners should work though. Latest build ? https://builder.blender.org/download/
Thank you, Hadriscus, I used your link and downloaded the latest build to replace the one I had. I find if I use the lower corners, I can get the little plus sign and create new windows, but still can’t close them. Thank you for the tip about right-clicking on the line to join windows. That works well. Would you please tell me how to close them with the corners? I’m sure I must be misunderstanding how it’s done. I’ve tried dragging from the corner in every direction and all I can do is make more windows. 
It should work by dragging from the corner, towards the separating line. It’s not obvious how they made this behave in 2.8, hardly discoverable and always finnicky to get right on the first try…
Ah! Thank you, that was it! Thank you so much, Hadriscus! Yes, it is finnicky, but I get it now. 