We use prefilters a lot as “switches”. When the prefilter is switch on we would like to change not only it's background but the icon to another one and when it's “inactive” change the icon back to its default. Let say like styling with CSS “:active:focus”
I think it would be a great feature for all customers. We all use “On/Off” pre-filters and let us create 2 icons “Button ON / Button OFF” icons or “Green / Red”, “Switch ON / Off” etc.