arcgis web appbuilder - How to debug settings page of custom widgets?

I'm developing a setting page for my widget. To debug it, I consulted the guide again and found this advice:

During development, use http://your host/webappbuilder/?appid=stemapp to directly access your widget. This URL helps test the configuration page of the widget.

So I tried to open my builder with ?appid=stemapp query string. I got the list of my apps as though there was no query string. The only difference is that when I open an app from this page the loading lasts forever, not few seconds as when opened from the normal WAB root. This doesn't seem to be the direct access for my widget. Google on web appbuilder "appid=stemapp" found only the guide and two pages citing it, so it's possible that it is just a documentation error and the direct widget access either doesn't exist or is somewhere else.

So, do I have any better options for setting page debugging than app edit > widgets? While editing the app, especially early stages of the debugging are frustrating, Create widget setting page error:widget/MyWidget/Widget is not very helpful.

I reposted this on the ESRI support forum.

Answer

I received an answer by Robert Scheitlin, one of ESRI's main WAB experts:

I develop widget all the time and I never use that from the guide. Here is my workflow:

https://geonet.esri.com/message/576495#comment-576497

So, do I have any better options for setting page debugging than app edit > widgets?

Not that I have found.

Later, Robert explained what "to directly access your widget" exactly means: we can work directly with stemapp as though it was a custom app. The documentation is almost correct, as Robert wrote:

I have done some testing and it seems that there is an error in the guide the url is actually:

http://localhost:3344/webappbuilder/?id=stemapp

Notice the parameter is id not appid