RE: [mediaqueries] reevaluating media queries when the environment changes

> MQ4 states:
> "User agents should re-evaluate media queries in response to changes in the user environment"
> MQ3 has the same, phrased differently.
> I believe this was intentional, but I cannot think of any good reason for using should rather than must in this sentence, and would like to change.

>The only two reasons I can think of are:
>1) If we write MUST, this will delay MQ3 getting to REC

> If that's the case, this is no longer relevant, and we can use must

> 2) We want to allow some user agents to layout and render a static view of the page once, and then never touch it again (no relayout, no interaction, no javascript after the initial load...).

>If that's what we want to do, we can carve out a specific exemption for such UAs, without allowing normal interactive browsers to fail to update their media queries when something changes.

I think this would be best to stay as 'SHOULD' as that implies your desired end result while keeping us from forcing a 'MUST' on all current or future MQs. I think if you want to be more explicit than this, then each MQ evaluation type should be listed and whether or not they 'SHOULD' or 'MUST' be re-evaluated on environment change.

Greg