Noone reported yet such message, but there's bug with 'no enough room to display document'. Is your Tools Bar undocked?
I didn't sent him to one of many topics about problem with displaying document as he says he's getting other message, so similar one, but not the same: "to dock it". So shortly saying that one you linked is about other thing than he's experiencing.
I could not find or think of an error message about "docking", so I think he meant "document" instead of "dock". He'll let us know or drop a screenshot.
I had someone tell me he was having a problem with the "Drag Tool", so I don't always expect posters to get terms or error messages 100% correct. If it doesn't seem right I offer the alternative instead of accepting what was said.
This issue should be fixed in the Photoshop CC 2018 (19.1.4) release which is now available. Checkout the list of fixed issues here: Fixed issues in Adobe Photoshop CC
Please update Photoshop CC 2018 via the Creative Cloud desktop app and let us know if you continue to have any trouble.
After 3 months if finally works again!