URL I'm talking about: https://chromiumdash.appspot.com/schedule

Quick FYI: iOS will be present in the dropdown list soon, we recently added support.

Re: functionality: The dropdown for platform is used to determine which milestone is currently in dev / beta / stable respectively, which populates the initial list of items (e.g. if M60 is in stable it shows that first) - it was not intended to tweak the list of platform owners for your second red arrow.  So the only time it'll do anything is when platforms differ in what is currently shipping to stable, and it'd only change which milestone is used as the first index of the list.  Since those are the same across all platforms now, they all look identical.

That said I think the value provided by the dropdown is minimal and likely is confusing folks more than it helps.  Do you think removing the dropdown would be beneficial on this view?  That's the direction I'm leaning based on your feedback.

Marking this as fixed because we've removed the platform selector from the staging instance: https://chromiumdash-staging.googleplex.com/schedule

We'll be pushing this version live in ~1 month, so you won't see the update immediately.