I Think is essential to use external WMS services as basemap gallery .
In AGOL i can load a WMS in a web map as basemap , create a WMS map element and share this in a webmap gallery but in any webapplication template (WAB included) i can see and use these elements in my basemap gallery widget).
It's very frsutrating... !!!!!!!!!!!!!!!!!!!!
Any suggestion or news from ESRI Folk is very appreciated
Enrico
