[admax88q]

The "system is not hung" signal is dead now due to modern platforms making sure that nothing happens on the UI thread. Now we get buttery smooth 60 fps spinners and loading bars, but if the thread doing the real work hangs, there's no indication.

[TeMPOraL]

Exactly this. And spinner gifs are particularly useless, because they're that - gifs. Not progress indicators that need to be explicitly told by code to spin a bit more. Just fire-and-forget animations, that will keep to spin forever even if your processing code dies.