Hi Klaus and your team!
I'm having a question, or it's maybe a bug of your software. In this showcase, I use the "onpreviewcomplete" to hide the loading screen, which is a html code outsite of krpano. It works pretty well in good internet connection, but sometimes or in a poor connection, the loading screen was hidden before the preview images be loaded. I tested in both CDN-based and not CDN-based images and got the same result. You can recreate that situation by throtling the connection using the default Developer tools on any common browsers.
Thanks a lot!
Sorry for my bad English