The Tile had a wrong size on Windows 10.
I updated the app solving also a bug letting crash the app on startup. Hope the viewer works fine now on Windows 8.1 and Windows 10!

This viewer works only if a friend of you or yourself have the SYNC-Addon!

If you have Windows 10, you can download the app with this link:
https://www.microsoft.com/store/apps/9wzdncrfj8vq

On Windows 8.1:
http://apps.microsoft.com/windows/app/b719f355-e524-4e0a-863a-5f57428f2f5c

To see what you can do with the Sync addon, open this blog page:
The power of the SYNC-Addon