Thanks,
Yes, I want to use it with WebViewer.
I installed WebViewTools extension wich has so many methods but not the one described.
I need to enable this option to make OPENCART works on webviewer. Many post on the web state that in this case putting a
setDomStorageEnabled(true) in MainActivity.java would solves the problem.
But they don't refer to APP INVENTOR of course.
I'm looking for a solution, in the meanwhile, thanks for your answer.