Accidentely I closed the error list. I would expect to get it back by selecting View -> Error list, but nothing happens. When I close all screen elements and choose View -> Project Explorer, the project explorer appears, same for Properties and Toolbox but Console + Error List don't come back. Restarting Mendix didn't solve the problem either. Luckily a Mendix guy who is here today helped me out by removing some lines from the user.config, but it would be a nice feater to have a View -> Reset Interface option.
What version are you working with? I closed my error list and went to View -> Error list and it worked as expected.
Robert van 't Hof
I've also noticed this. Sometimes it happens, but mostly not.