[css-ui-3] handling unsupported cursor values

I've been writing tests about css-ui-3's cursor, which made me review the spec prose closer than before.

The spec contains this sentence:

  "The UA may treat unsupported values as auto.
   E.g. on platforms that do not have a concept
   of a context-menu cursor, the UA may render
   default or whatever is appropriate."


I think this is bad:

a- as a general error handling mechanism in css, when you don't support a value, you should fail to parse it, so that authors can use the cascade for fallbacks.

b- "whatever is appropriate" is not something the UA can determine in this case. The only thing it know about the author's intent is that they want a context-menu cursor, and possibly which fallbacks they want if this value is not supported. 

c- regardless of whether the platform has a concept of a context menu, my web app may have one. I don't want the browser to second-guess what I want based on OS behavior.

I think we should either simply delete this sentence so that normal error handling applies, or if we want to be explicit (as we've been with outline-color), write this:

  "The UA must reject unsupported values at parse-time."

 - Florian

Received on Wednesday, 17 June 2015 12:45:52 UTC