Hello,
There isn't a option that does this directly. Whenever autoplay is activated, it will go through the frames exactly once and then stop.
It is possible to use our event system to loop the gallery forever, but this makes the autoplay impossible to ever stop. (Normally, when the user swipes to a different frame during an autoplay, the autoplay will be cancelled, but not if you do this.) If this is still useful in your case, this is how it can be done:
- Add a gallery component to your document, and add images.
- Press the [+] button in the Events panel to define a new event handler.
- Select event target: your gallery
- Select event type: gallery -> frame shown
- Select action: gallery -> rotate once
- Select receiver: your gallery
- Enter the desired rotation duration.
- Save

This simply starts the autoplay every time a new frame is shown, so that it can never stop.
Thanks for expressing your interest in this feature. Other users have also requested a built-in option to autoplay forever, while still allowing the user to interrupt it. We'll consider it for inclusion in a future release.
Cheers,
Jeremy Banks
GWD Software Engineer