This article describes the official policy of the Ultrastudio.org website. It is not editable.
The applet screen shoot is a derived work of the applet as a software, and the most obvious way to share it is to share under the same license as the applet itself. One screen shoot is normally bound to the particular applet. It can be easily identified by name. If alternative screen shoots are uploaded, the exact home page of the applet must be specified.
This licensing option is only possible when uploading screen shoots to the applets that have already been submitted at least for reviewing in this website.
There is no such thing as "abstract applet screen shot license". For every real world case, the original license of the applet itself applies.