Are we sure this is the behavior we want? It means someone can't build a "pick your top 3" listbox that actually ranks the first, second, third place choices

Hmm, interesting. I'm not sure how important it is to maintain the order of the source options. I believe it was Kristiyan who proposed this change. @crisbeto could you weigh in here?

The context here is that mat-select used to keep the selection order and we had to introduce the sorting, because users found it confusing that going into a multi-select and checking a bunch of stuff could lead to different results each time. There might also be some implications for the data the app submits to the server.

FWIW in mat-select we also have an input that allows users to customize the sorting which we could introduce here.

I think I'll leave it unsorted for now and wait for feedback from the community on this one. It's easier to add this feature in the future than it would be to remove it. I'm also not convinced we should add a hook for sorting since signals makes it trivial for devs to implement this by just using computed

Yeah I think it depends on what you're implementing, for a standard <select multiple> there's no meaning to the order, so it makes sense to order them, but it feels like something that should be up to the developer based on the use case.