Joining two windows doesn't work [duplicate]

I click join area and then the Area Options dialog disappears and nothing happens.

• Close the timeline first Aug 13, 2015 at 2:00
• If you look at the system console, you will see an error printed: areas don't share edge. You can only join areas if the fully share an edge, but in your case the right-hand area shares an edge with two other areas. Aug 13, 2015 at 13:32