I need to add loading icon (gif) to an in-panel Web Appbuilder custom widget, which like "Url Link Button" widget, does not have an explicit html file.
I saw a solution by Robert Scheitlin in this blog in url
Add loading icon to url button custom widget
I tried, but it turns that esri/dijit/util/busyIndicator is not available anymore in javascript API 4.15 ...
I saw a 2nd approach by Robert Scheitlin in this blog in url
Show loading message while the widget is doing operations
but it does not operate for me either. no errors, but does not work...