It is not the verbose flag. I got the information that with MATLAB/SIMULINK R2015a a new UI 'Diagnostic Viewer' has been introduced, see https://uk.mathworks.com/help/simulink/ug/diagnose-simulation-errors.html.
To view the diagnostic window one can click “View diagnostics” which appears at the bottom of the model window at build time.
You can also select a web site from the following list:
How to Get Best Site Performance
Select the China site (in Chinese or English) for best site performance. Other MathWorks country sites are not optimized for visits from your location.