Hey, you could try this:
- Make a new material, change it to ‘user interface’
- Use Flipbook node, hook up your texture there, rows, columns etc.
- Open your Widget. Create an empty image.
- Texture it with the material you created.
You can specify a specific frame or start or end by using for example material parameter collections. By default it will just loop.
It’s better to do it 's way, though, if it was to be as simple as the gif you posted.