UseCounter data is hovering around 0.03% of pages: https://www.chromestatus.com/metrics/feature/timeline/popularity/873

I _think_ that makes deprecation/removal pretty unlikely (but we could do some research to verify).

Luna, from my perspective the "deprecated" warnings in specs don't really mean much for implementations.  If the IDL is still in the spec at all, then us shipping the API probably isn't a bug.  Why is the IDL tool flagging cases like this?

IMHO the only reason to mark an API deprecated in a spec is to discourage developers from using it for new things.  Thought I guess it's a good idea to at least ensure we have UseCounters for every spec-deprecated API and ask the question: "is this something that could make sense to remove?".

The spec doesn't actually define the arguments of initUIEvent(). I'll change the issue title to favor standardizing it while keeping the door open for other outcomes.

Opened issue https://github.com/w3c/uievents/issues/133.

Assigning to Gary. Feel free to close this issue if the spec issue is now open.

rbyers, the idl tool link to the spec at https://w3c.github.io/uievents/

Where only three top-level-attributes are included:
detail, view, and sourceCapabilities, which is why initUiEvent was captured as a non-standard API.

markdittmer, could you please look into this?

Thanks