GtkSpinner should spin even if animations are disabled
When GTK animations are disabled globally (e.g. via the Tweak Tool), GtkSpinner widgets don't spin and simply display the first frame of the spinning animation instead.
This looks horribly broken and makes no sense at all. The purpose of GtkSpinner is – according to the docs – to "show a spinner animation". If it doesn't spin, it's not a spinner anymore, and might as well be hidden entirely.
Just as progress bars still advance and videos still play, spinners should be unaffected by the global animation switch.