AnimatedIcon can read both, large pictures with the animation frames next to each other, while the real picture dimensions must be give in the tooltypes, and also real gif anims.
The AmigaOS 3.9 GIF datatype can of course read GIF pictures and it presents GIF animations to the application a a multi-image file. So programs like AnimatedIcon can extract each animation frame from the file and display it.
AnimatedIcon ony works with the original AmigaOS 3.9 GIF datatype. There is a GIFANIM datatype on Aminet that presents GIF animations as real animations. This does not work with AnimatedIcon or any other picture viewer.
I also saw that some optimised GIF anims are corrupted by the GIF datatype. But most animations work though.
Bye,
Thomas