Sorry if this has been asked elsewhere, but I looked and though found some similar things about grouping layers in AGOL but could not find thread with this exact question as it relates to WAB.
Environment: ArcGIS Portal for Server (v10.3.1) and WABr Dev Edition (v2.1)
I have dozens of editable layers that are grouped into sub-folders in the MXD and in the published map services. The editable feature service ends up with all the layers ungrouped.
When you create a Web Map in Portal that includes both the map service (with the layers grouped) and the feature service (layers ungrouped), the web map layer list appears to recognize that the map service and feature service are related and so presents a single set of layers grouped in their original subfolders (screenshot below):
However, when the Web Map is brought into WAB, this all goes out the window and the editable feature service layers lose their groupings and are just listed out in the layer list as one big list with no folders, and then the non-editable map service with the sub-folders is shown a the bottom of the list (see screenshot below). ( It seems like ESRI has figured out how to make this work in the Portal Web Map viewer app, so not sure why the WAB Layer List does not behave this way!)
Question: Ideally I am looking for a way we could edit the Layer List widget so that the groupings would stay in place, and alternately, as possibly acceptable work around, I would be looking for how to have the non-editable map services show up a the top of the Operational layers and have the giant ungrouped list of editable feature services listed below them (this way the user doesn't have to scroll all the way through the giant list of editable layers just to get to the main map service).
About WAB Dev Edition (v2.1), LayerList setting page support to configure which layers will be shown or hidden on the LayerList. So you could hide editable layers manually. This design is more flexible, because of there are users really want to show both editable and non-editable layers.
Thanks for the suggestion, I had started to look in this direction. It seems like you have to set it so that you hide all the editable feature layers from the layer list, while at the same time you leave them checked as "visible" on the map (else they don't show up on the editor template list). I guess the possible downside of this approach is that the user can create situation where the visibility of the editable and non-editable version of the layer don't match. For example they can turn off the non-editable version of the 911Calls Hotspot Output_Features, but nothing prevents them from creating new Output_Features using the editor widget, and these new features won't be displayed on the map until they realize that they need to turn the non-editable version of the layer back on to see the new features. In the Portal/AGOL Web Map viewer app, this can't happen because the editable and non-editable version of the layers are always turned on/off at same time. But I think that this work around is probably my best bet for time being, and I will make end users are aware that they must have the non-editable version of layer turned on as well.